Printer

ABSTRACT

Provided is a printer including an ink tank, a print head performing printing by using ink in the ink tank, a light source provided at the substrate and irradiating the ink tank with light from a side of the ink tank, a photoelectric conversion device provided at the substrate and detecting light incident from the ink tank in a period during which the light source emits light, and a processing unit detecting an amount of ink based on an output of the photoelectric conversion device.

The present application is based on, and claims priority from JPApplication Serial Number 2019-022314, filed Feb. 12, 2019, thedisclosure of which is hereby incorporated by reference herein in itsentirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a printer and the like.

2. Related Art

In the related art, there is known a method for determining whether inkis present in an ink container in a printer that performs printing byusing ink. For example, in JP-A-2001-105627, an ink supply device thatdetects a liquid level of ink by receiving light emitted from a lightemitter and passing through an ink bottle by using a light receiver isdisclosed.

Further improvements of the printer have been desired.

SUMMARY

An aspect of the present disclosure relates to a printer including: anink tank, a print head performing printing by using ink in the ink tank,a substrate, a light source provided at the substrate and irradiatingthe ink tank with light from a side of the ink tank, a photoelectricconversion device provided at the substrate and detecting light incidentfrom the ink tank in a period during which the light source emits light,and a processing unit detecting an amount of ink in the ink tank basedon an output of the photoelectric conversion device. In theconfiguration using transmitted light, it is necessary to provide alight emitting unit and a light receiving unit in different directionswith respect to the ink tank, but in this aspect, a member for inkamount detection can be efficiently disposed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective diagram illustrating a configuration of anelectronic apparatus.

FIG. 2 is a diagram for explaining an arrangement of ink tanks in theelectronic apparatus.

FIG. 3 is a perspective diagram of the electronic apparatus in a statewhere a lid of an ink tank unit is opened.

FIG. 4 is a perspective diagram illustrating a configuration of the inktank.

FIG. 5 is a diagram illustrating a configuration example of a printerunit and the ink tank unit.

FIG. 6 is an exploded diagram of a sensor unit.

FIG. 7 is a diagram illustrating a positional relationship between asubstrate, a photoelectric conversion device, and a light source.

FIG. 8 is a sectional diagram of the sensor unit.

FIG. 9 is a diagram for explaining a positional relationship between theink tank, the light source, and the photoelectric conversion device.

FIG. 10 is a diagram for explaining a positional relationship betweenthe light source and a light guide.

FIG. 11 is a diagram for explaining a positional relationship betweenthe light source and the light guide.

FIG. 12 is a diagram for explaining a positional relationship betweenthe light source and the light guide.

FIG. 13 is a diagram illustrating a configuration example of the sensorunit and a processing unit.

FIG. 14 is a diagram illustrating a configuration example of thephotoelectric conversion device.

FIG. 15 is a perspective diagram of an electronic apparatus including awindow portion.

FIG. 16 is a schematic diagram when a lens array is provided as anoptical separator.

FIG. 17 is a schematic diagram when a resin slit is provided as anoptical separator.

FIG. 18 is a schematic diagram when an optical separator is provided ona side surface of an ink tank.

FIG. 19 is a diagram illustrating a configuration example of an opticalseparator provided on a side surface of an ink tank.

FIG. 20 is a diagram illustrating a configuration example of an opticalseparator provided on a side surface of an ink tank.

FIG. 21 is a diagram illustrating a configuration example of an opticalseparator provided on a side surface of an ink tank.

FIG. 22 is a schematic diagram when an optical separator is omitted.

FIG. 23 is a diagram for explaining a positional relationship between alight source and a light guide.

FIG. 24 is a diagram for explaining a positional relationship between alight source, a light guide, and a photoelectric conversion device.

FIG. 25 is a diagram for explaining a positional relationship between anink tank, a light source, and a photoelectric conversion device.

FIG. 26 is an exploded diagram of a light receiving unit.

FIG. 27 is an exploded diagram of a light emitting unit.

FIG. 28 is a diagram for explaining a positional relationship between anink tank, a light source, and a photoelectric conversion device.

FIG. 29 is an exploded diagram illustrating another configuration of asensor unit.

FIG. 30 is a sectional diagram illustrating another configuration of asensor unit.

FIG. 31 is a diagram illustrating an example of output data of aphotoelectric conversion device.

FIG. 32 is a flowchart for explaining ink amount detection processing.

FIG. 33 is a schematic diagram illustrating an ink tank to which an inkdroplet is attached and output data at that time.

FIG. 34 is a flowchart for explaining ink amount detection processing inconsideration of an ink droplet.

FIG. 35 is a diagram for explaining correction processing with respectto output data.

FIG. 36 is a schematic diagram for explaining an assembly error.

FIG. 37 is a diagram for explaining ink amount detection processingbased on a mark.

FIG. 38 is a schematic diagram illustrating an ink tank with a mark andoutput data.

FIG. 39 is a diagram illustrating an example of a relationship between aslit and a mark provided on a side surface of an ink tank.

FIG. 40 is a schematic diagram when a photoelectric conversion device isinclined with respect to an ink tank.

FIG. 41 is a schematic diagram when a plurality of photoelectricconversion devices are provided in a horizontal direction with respectto one ink tank.

FIG. 42 is an explanatory diagram of a method for detecting aninclination of a photoelectric conversion device with respect to an inktank.

FIG. 43 is an explanatory diagram of a method for detecting aninclination of an ink tank with respect to a horizontal plane.

FIG. 44 is a diagram illustrating a relationship between output data ofyellow ink and output data of magenta ink.

FIG. 45 is a diagram illustrating a relationship between output data ofmagenta dye ink and output data of magenta pigment ink.

FIG. 46 is a perspective diagram of an electronic apparatus when ascanner unit is used.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the present embodiments will be described. The presentembodiments described below do not unduly limit the content described inclaims. Also, not all configurations described in the present embodimentare essential configuration requirements.

1. Configuration Example of Electronic Apparatus

1.1 Basic Configuration of Electronic Apparatus

FIG. 1 is a perspective diagram of an electronic apparatus 10 accordingto the present embodiment. The electronic apparatus 10 is amulti-function peripheral (MFP) including a printer unit 100 and ascanner unit 200. The electronic apparatus 10 may have other functionssuch as a facsimile function in addition to a printing function and ascanning function. Alternatively, only the printing function may beprovided without a scanning function. The electronic apparatus 10includes an ink tank unit 300 that accommodates ink tanks 310. Theprinter unit 100 is an ink jet printer which executes printing by usingink supplied from the ink tanks 310. Hereinafter, the description of theelectronic apparatus 10 can be appropriately replaced with a printer.

FIG. 1 illustrates a Y-axis, an X-axis orthogonal to the Y-axis, and aZ-axis orthogonal to the X-axis and the Y-axis. In each of the XYZ axes,a direction of an arrow indicates a positive direction, and a directionopposite from the direction of the arrow indicates a negative direction.Hereinafter, the positive direction of the X-axis is described as +Xdirection and the negative direction is described as −X direction. Thesame applies to the Y-axis and the Z-axis. The electronic apparatus 10is disposed on a horizontal plane defined by the X-axis and the Y-axisin a use state, and the +Y direction is the front of the electronicapparatus 10. The Z-axis is an axis orthogonal to the horizontal plane,and −Z direction is vertically downward direction.

The electronic apparatus 10 has an operation panel 101 as a userinterface unit. The operation panel 101 is provided with buttons forperforming, for example, an ON/OFF operation of a power supply of theelectronic apparatus 10, an operation related to printing using theprinting function, and an operation related to reading of a documentusing the scanning function. The operation panel 101 is also providedwith a display unit 150 for displaying an operating state of theelectronic apparatus 10 and a message or the like. Further, the displayunit 150 displays the ink amount detected by the method described later.Further, the operation panel 101 may be provided with a reset button forthe user to replenish ink in the ink tank 310 to execute resetprocessing.

1.2 Printer Unit and Scanner Unit

The printer unit 100 performs printing on a printing medium P such asprinting paper by ejecting ink. The printer unit 100 has a case 102which is an outer shell of the printer unit 100. On a front side of thecase 102, a front cover 104 is provided. Here, the “front” represents aface on which the operation panel 101 is provided and represents a facein +Y direction of the electronic apparatus 10. The operation panel 101and the front cover 104 are pivotable around the X-axis with respect tothe case 102. The electronic apparatus 10 includes a paper cassette (notillustrated), and the paper cassette is provided in the −Y directionwith respect to the front cover 104. The paper cassette is coupled tothe front cover 104 and detachably attached to the case 102. A paperdischarge tray (not illustrated) is provided in the +Z direction of thepaper cassette, and the paper discharge tray can be expanded andcontracted in the +Y direction and the −Y direction. The paper dischargetray is provided in the −Y direction with respect to the operation panel101 in the state illustrated in FIG. 1, and exposed to the outside bythe pivoting of the operation panel 101.

The X-axis is a main scanning axis HD of a print head 107, and theY-axis is a sub-scanning axis VD of the printer unit 100. A plurality ofprinting media P are placed in a stacked state on the paper cassette.The printing media P placed on the paper cassette are supplied one byone into the case 102 along the sub-scanning axis VD, printed by theprinter unit 100, discharged along the sub-scanning axis VD, and placedon the paper discharge tray.

The scanner unit 200 is mounted on the printer unit 100. The scannerunit 200 has a case 201. The case 201 constitutes the outer shell of thescanner unit 200. The scanner unit 200 is of a flat bed type and has adocument table formed of a transparent plate-like member such as glassand an image sensor. The scanner unit 200 reads an image or the likerecorded on a medium such as paper as image data via an image sensor.The electronic apparatus 10 may be provided with an automatic documentfeeder (not illustrated). The scanner unit 200 sequentially feeds aplurality of stacked documents while reversing them one by one by theautomatic document feeder, and reads them by using the image sensor.

1.3 Ink Tank Unit and Ink Tank

The ink tank unit 300 has a function of supplying ink IK to the printhead 107 included in the printer unit 100. The ink tank unit 300includes a case 301, and the case 301 has a lid 302. A plurality of inktanks 310 are accommodated in the case 301.

FIG. 2 is a diagram illustrating a state of the ink tanks 310 beingaccommodated. A portion indicated by a solid line in FIG. 2 representsthe ink tanks 310. A plurality of inks IK of different kinds areindividually accommodated in the plurality of ink tanks 310. That is,different kinds of inks IK are accommodated in the plurality of inktanks 310 for each ink tank 310.

In the example illustrated in FIG. 2, the ink tank unit 300 accommodatesfive ink tanks 310 a, 310 b, 310 c, 310 d, and 310 e. In the presentembodiment, five kinds of inks are adopted, as the kinds of inks: twokinds of black inks, color inks of yellow, magenta, and cyan. Two kindsof black inks are pigment ink and dye ink. Ink IKa which is blackpigment ink is accommodated in the ink tank 310 a. The respective colorinks IKb, IKc, and IKd of yellow, magenta, and cyan are accommodated inthe ink tanks 310 b, 310 c, and 310 d. Ink IKe which is a black dye inkis accommodated in the ink tank 310 e.

The ink tanks 310 a, 310 b, 310 c, 310 d, and 310 e are arranged side byside in this order along the +X direction, and fixed in the case 301.Hereinafter, when the five ink tanks 310 a, 310 b, 310 c, 310 d, and 310e and the five kinds of inks IKa, IKb, IKc, IKd, and IKe are notdistinguished, they are simply expressed as the ink tank 310 and the inkIK.

In the present embodiment, ink IK is configured to be able to be filledinto the ink tank 310 from the outside of the electronic apparatus 10 bythe user for each of the five ink tanks 310. Specifically, the user ofthe electronic apparatus 10 fills ink IK accommodated in anothercontainer into the ink tank 310 from an ink filling port 311 to performreplenishment.

In the present embodiment, the capacity of the ink tank 310 a is largerthan the capacities of the ink tanks 310 b, 310 c, 310 d, and 310 e. Thecapacities of the ink tanks 310 b, 310 c, 310 d, and 310 e are the sameas each other. In the printer unit 100, it is assumed that the blackpigment ink IKa is consumed more than that of the color inks IKb, IKc,and IKd and the black dye ink IKe. The ink tank 310 a accommodating theblack pigment ink IKa is disposed at a position close to the center ofthe electronic apparatus 10 on the X-axis. In this way, for example,when the case 301 has a window portion 103 as illustrated in FIG. 15described later, the remaining amount of ink that is frequently used iseasily confirmed. However, the arrangement order of the five ink tanks310 a, 310 b, 310 c, 310 d, and 310 e is not particularly limited. Whenany one of the other inks IKb, IKc, IKd, and IKe is consumed more thanthe black pigment ink IKa, the ink IK may be accommodated in the inktank 310 a of a large capacity.

FIG. 3 is a perspective diagram of the electronic apparatus 10 in astate where the lid 302 of the ink tank unit 300 is opened. The lid 302is pivotable with respect to the case 301 via a hinge portion 303. Whenthe lid 302 is opened, five ink tanks 310 are exposed. Morespecifically, five caps corresponding to each ink tank 310 are exposedby opening the lid 302, and a portion of the ink tank 310 in the +Zdirection is exposed by opening the caps. A portion of the ink tank 310in the +Z direction is an area including an ink filling port 311 of theink tank 310. When the ink IK is filled into the ink tank 310, the useraccesses the ink tank 310 by pivoting the lid 302 and opening it upward.

FIG. 4 is a diagram illustrating the configuration of the ink tank 310.Each axis of X, Y, and Z in FIG. 4 indicates an axis in a state wherethe electronic apparatus 10 is used in a normal posture and the ink tank310 is appropriately fixed to the case 301. Specifically, the X-axis andthe Y-axis are axes along the horizontal direction, and the Z-axis is anaxis along a vertical direction. For each axis of XYZ, unless otherwisespecified, the same shall apply in the following drawings. The ink tank310 is a three-dimensional body in which the ±X direction is a shortside direction and the ±Y direction is a longitudinal direction.Hereinafter, of the surfaces of the ink tank 310, a surface in the +Zdirection is referred to as an upper surface, a surface in the −Zdirection is referred to as a bottom surface, and surfaces in the ±Xdirection and ±Y direction are referred to as side surfaces. The inktank 310 is formed of a synthetic resin such as nylon or polypropylene,for example.

When the ink tank unit 300 includes a plurality of ink tanks 310 asdescribed above, each of the plurality of ink tanks 310 may beconfigured separately or may be configured integrally. When the ink tank310 is integrally configured, the ink tank 310 may be integrally formed,or a plurality of ink tanks 310 formed separately may be integrallybundled or coupled together.

The ink tank 310 includes the filling port 311 into which ink IK isfilled by the user, and a discharging port 312 for discharging the inkIK toward the print head 107. In the present embodiment, the uppersurface of the portion on the +Y direction side that is a front side ofthe ink tank 310 is higher than the upper surface of the portion on the−Y direction side that is a rear side. The filling port 311 for fillingink IK from the outside is provided on the upper surface of the portionon the front side of the ink tank 310. The filling port 311 is exposedby opening the lid 302 and the cap as described above with reference toFIG. 3. The ink IK of each color can be replenished to the ink tank 310by filling the ink IK from the filling port 311 by the user. The ink IKfor the user to replenish the ink tank 310 is accommodated and providedin a separate replenishing container. The discharging port 312 forsupplying ink to the print head 107 is provided on the upper surface ofthe portion on the rear side of the ink tank 310. Since the filling port311 is provided on the side close to the front of the electronicapparatus 10, filling of the ink IK can be facilitated.

1.4 Other Configurations of Electronic Apparatus

FIG. 5 is a schematic configuration diagram of the electronic apparatus10 according to the present embodiment. As illustrated in FIG. 5, theprinter unit 100 according to the present embodiment includes a carriage106, a paper feed motor 108, a carriage motor 109, a paper feed roller110, a processing unit 120, a storage unit 140, the display unit 150, anoperation unit 160, and an external I/F unit 170. In FIG. 5, thespecific configuration of the scanner unit 200 is omitted. FIG. 5 is adiagram exemplifying a coupling relationship between each part of theprinter unit 100 and the ink tank unit 300, and does not limit thephysical structure or the positional relationship of each part. Forexample, in the arrangement of members such as the ink tank 310, thecarriage 106, and a tube 105 in the electronic apparatus 10, variousembodiments can be considered.

The print head 107 is mounted on the carriage 106. The print head 107has a plurality of nozzles for ejecting ink IK in the −Z direction onthe bottom surface side of the carriage 106. The tube 105 is providedbetween the print head 107 and each ink tank 310. Each ink IK in the inktank 310 is sent to the print head 107 via the tube 105. The print head107 ejects each ink IK sent from the ink tanks 310 to the printingmedium P from the plurality of nozzles as ink droplets.

The carriage 106 is driven by the carriage motor 109 to reciprocatealong the main scanning axis HD on the printing medium P. The paper feedmotor 108 rotationally drives the paper feed roller 110 to transport theprinting medium P along the sub-scanning axis VD. The ejection controlof the print head 107 is performed by the processing unit 120 via acable.

In the printer unit 100, printing is performed on the printing medium Pby the carriage 106 ejecting the ink IK from the plurality of nozzles ofthe print head 107 to the printing medium P transported to thesub-scanning axis VD while moving along the main scanning axis HD, basedon the control of the processing unit 120.

One end portion of the carriage 106 on the main scanning axis HD in amoving area is a home position area where the carriage 106 stands by. Inthe home position area, for example, a cap or the like (not illustrated)for performing maintenance such as cleaning the nozzle of the print head107 is disposed. Also, a waste ink box for receiving waste ink whenflushing or cleaning of the print head 107 is performed is disposed inthe moving area of the carriage 106. The flushing means that ink IK isejected from each nozzle of the print head 107 regardless of printingduring printing of the printing medium P. The cleaning means cleaningthe inside of the print head by sucking the print head by a pump or thelike provided in the waste ink box, without driving the print head 107.

Here, an off-carriage type printer in which the ink tank 310 is providedat a location different from the carriage 106 is assumed. However, theprinter unit 100 may be an on-carriage type printer in which the inktank 310 is mounted on the carriage 106 and moved along the mainscanning axis HD together with the print head 107. For example, in aprinter for monochrome printing having one ink tank 310, the amount ofink IK to be accommodated is small, and even when the ink tank 310 ismounted on the carriage 106, the carriage is easily driven. Of course,also in a printer capable of color printing, the ink tank 310 may bemounted on the carriage 106.

The operation unit 160 and the display unit 150 as a user interface unitare coupled to the processing unit 120. The display unit 150 is fordisplaying various display screens and can be realized by, for example,a liquid crystal display or an organic EL display. The operation unit160 is for the user to perform various operations and can be realized byvarious buttons, GUI, or the like. For example, as illustrated in FIG.1, the electronic apparatus 10 includes the operation panel 101, and theoperation panel 101 includes the display unit 150 and a button or thelike as the operation unit 160. The display unit 150 and the operationunit 160 may be integrally configured by a touch panel. When the useroperates the operation panel 101, the processing unit 120 operates theprinter unit 100 and the scanner unit 200.

For example, in FIG. 1, the user operates the operation panel 101 tostart operation of the electronic apparatus 10 after setting a documenton a document table of the scanner unit 200. Then, the document is readby the scanner unit 200. Subsequently, based on the image data of theread document, the printing medium P is fed from the paper cassette intothe printer unit 100, and printing is performed on the printing medium Pby the printer unit 100.

An external device can be coupled to the processing unit 120 via theexternal I/F unit 170. The external device here is, for example, apersonal computer (PC). The processing unit 120 receives the image datafrom the external device via the external I/F unit 170, and performscontrol for printing the image on the printing medium P by the printerunit 100. In addition, the processing unit 120 controls the scanner unit200 to read the document and transmit the image data as a reading resultto the external device via the external I/F unit 170, or to print theimage data as the reading result.

The processing unit 120 performs, for example, drive control,consumption calculation processing, ink amount detection processing, andink characteristics determination processing. The processing unit 120 ofthe present embodiment is configured by the following hardware. Thehardware can include at least one of a circuit for processing a digitalsignal and a circuit for processing an analog signal. For example, thehardware can be configured by one or more circuit devices mounted on thecircuit substrate or one or more circuit elements. The one or morecircuit devices are, for example, ICs or the like. The one or morecircuit elements are, for example, resistances, capacitors, or the like.

The processing unit 120 may be realized by the following processor. Theelectronic apparatus 10 of the present embodiment includes a memory thatstores information, and a processor that operates based on informationstored in the memory. The information is, for example, a program andvarious kinds of data. The processor includes hardware. As theprocessor, various processors such as a central processing unit (CPU),graphics processing unit (GPU), digital signal processor (DSP), or thelike can be used. The memory may be semiconductor memory such as staticrandom access memory (SRAM), dynamic random access memory (DRAM), or thelike, and may be a register, or a magnetic storage device such as a harddisk device, or may be an optical storage device such as an optical diskdevice or the like. For example, the memory stores an instruction thatcan be read by a computer, and the function of each unit of theelectronic apparatus 10 is realized as processing by executing theinstruction by the processor. The instruction here may be an instructionof an instruction set constituting the program or an instruction forinstructing the operation to the hardware circuit of the processor. Inaddition, the processor and the memory may be integrated as asystem-on-a-chip (SOC).

The processing unit 120 controls the carriage motor 109 to perform drivecontrol for moving the carriage 106. Based on the drive control, thecarriage motor 109 drives to move the print head 107 provided on thecarriage 106.

The processing unit 120 performs the consumption calculation processingof calculating a consumption of ink consumed by ejecting the ink IK fromeach nozzle of the print head 107. The processing unit 120 starts theconsumption calculation processing with the state where each ink tank310 is filled with the ink IK as an initial value. More specifically,when the user replenishes the ink IK to the ink tank 310 and presses areset button, the processing unit 120 initializes a count value of theink consumption with respect to the ink tank 310. Specifically, thecount value of the ink consumption is set to 0 g. The processing unit120 starts the consumption calculation processing with the pressingoperation of the reset button as a trigger. The processing unit 120executes the consumption calculation processing for each ink tank 310.

The processing unit 120 performs ink amount detection processing ofdetecting the amount of ink IK accommodated in the ink tank 310, basedon the output of a sensor unit 320 provided corresponding to the inktank 310 one by one. The processing unit 120 performs inkcharacteristics determination processing of determining thecharacteristics of the ink IK accommodated in the ink tank 310, based onthe output of the sensor unit 320 provided corresponding to the ink tank310. Details of the ink amount detection processing and inkcharacteristics determination processing are described later.

1.5 Detailed Configuration Example of Sensor Unit

FIG. 6 is an exploded perspective diagram schematically illustrating theconfiguration of the sensor unit 320. The sensor unit 320 includes asubstrate 321, a photoelectric conversion device 322, a light source323, a light guide 324, a lens array 325, and a case 326.

The light source 323 and the photoelectric conversion device 322 aremounted on the substrate 321. The photoelectric conversion device 322 isa linear image sensor in which, for example, photoelectric conversionelements are arranged in a predetermined direction. The linear imagesensor may be a sensor in which photoelectric conversion elements arearranged in one row or a sensor in which photoelectric conversionelements are arranged in two or more rows. The photoelectric conversionelement is, for example, a photodiode (PD). A plurality of outputsignals based on a plurality of photoelectric conversion elements areacquired by using the linear image sensor. Therefore, not only whetherthe ink IK is present but also the position of the interface of the inkIK can be estimated.

The light source 323 has, for example, R, G, and B light emitting diodes(LED: Light emitting diode) and emits light sequentially while switchingthe R, G, and B light emitting diodes at high speed. The light emittingdiode of R is represented as a red LED 323R, the light emitting diode ofG is represented as a green LED 323G, and the light emitting diode of Bis represented as a blue LED 323B. The light guide 324 is a rod-likemember for guiding light, and the cross-sectional shape may be a squareshape, a circular shape, or another shape. The longitudinal direction ofthe light guide 324 is a direction along the longitudinal direction ofthe photoelectric conversion device 322. Since light from the lightsource 323 goes out from the light guide 324, the light guide 324 andthe light source 323 may be collectively referred to as a light source.

The light source 323, the light guide 324, the lens array 325, and thephotoelectric conversion device 322 are accommodated between the case326 and the substrate 321. The case 326 is provided with a first openingportion 327 for a light source and a second opening portion 328 for aphotoelectric conversion device. Light emitted from the light source 323enters the light guide 324, thereby the entire light guide emits light.Light emitted from the light guide 324 is emitted to the outside of thecase 326 through the first opening portion 327. Light from the outsideis inputted to the lens array 325 through the second opening portion328. The lens array 325 guides the input light to the photoelectricconversion device 322. Specifically, the lens array 325 has a Selfoclens array (Selfoc is a registered trademark) in which many refractiveindex distribution type lenses are arranged.

FIG. 7 is a diagram schematically illustrating the arrangement of thephotoelectric conversion devices 322. As illustrated in FIG. 7, n, nbeing an integer of 1 or more, photoelectric conversion devices 322 arearranged along a given direction on the substrate 321 side by side.Here, n may be 2 or more as illustrated in FIG. 7. That is, the sensorunit 320 includes a second linear image sensor provided on thelongitudinal direction side of the linear image sensor. The linear imagesensor is, for example, 322-1 in FIG. 7, and the second linear imagesensor is 322-2. Each photoelectric conversion device 322 is a chiphaving many photoelectric conversion elements arranged side by side asdescribed above. By using a plurality of photoelectric conversiondevices 322, a reading range for detecting incident light is widened,thereby a target range for detecting the ink amount can be widened.However, the number of linear image sensors, that is, the setting of thetarget range for detecting the ink amount can be performed in variousways, and may extend over the entire range of the liquid level of inkIK, may be a part of the range of the liquid level of the ink IK, or thenumber of the linear image sensors may be one.

FIG. 8 is a sectional diagram schematically illustrating the arrangementof the sensor units 320. As can be seen from FIGS. 6 and 7, although thepositions of the photoelectric conversion device 322 and the lightsource 323 do not overlap in the Z-axis, for convenience of describingthe positional relationship with other members, the light source 323 isillustrated in FIG. 8. As illustrated in FIG. 8, the sensor unit 320includes a light shielding wall 329 provided between the light source323 and the photoelectric conversion device 322. The light shieldingwall 329 is, for example, a portion of the case 326 and formed byextending a beam-like member between the first opening portion 327 andthe second opening portion 328 to the substrate 321. The light shieldingwall 329 shields direct light from the light source 323 toward thephotoelectric conversion device 322. Since incidence of the direct lightcan be suppressed by providing the light shielding wall 329, detectionaccuracy of the ink amount can be enhanced. It is preferable that thelight shielding wall 329 is capable of shielding direct light from thelight source 323 toward the photoelectric conversion device 322, and theconcrete shape is not limited to that in FIG. 8. A member separate fromthe case 326 is preferably used as the light shielding wall 329.

FIG. 9 is a diagram for explaining the positional relationship betweenthe ink tank 310 and the sensor unit 320. As illustrated in FIG. 9, thesensor unit 320 is fixed to any wall surface of the ink tank 310 in sucha posture that the longitudinal direction of the photoelectricconversion device 322 is the ±Z direction. That is, the photoelectricconversion device 322 as the linear image sensor is provided so that thelongitudinal direction goes along the vertical direction. Here, thevertical direction represents the gravity direction and the reversedirection when the electronic apparatus 10 is used in a proper attitude.

In the example illustrated in FIG. 9, the sensor unit 320 is fixed tothe side surface of the ink tank 310 in the −Y direction. That is, thesubstrate 321 provided with the photoelectric conversion device 322 iscloser to the discharging port 312 than the filling port 311 of the inktank 310. Whether printing in the printer unit 100 can be executeddepends on whether the ink IK is supplied to the print head 107.Therefore, by providing the sensor unit 320 on the discharging port 312side, the ink amount detection processing can be performed for aposition where the ink amount is particularly important in the ink tank310.

As illustrated in FIG. 9, the ink tank 310 may include a main container315, a second discharging port 313, and an ink flow path 314. The maincontainer 315 is a portion of the ink tank 310 that is used foraccommodating the ink IK. The second discharging port 313 is, forexample, an opening provided at a position in the most −Z direction inthe main container 315. However, various modifications can be performedfor the position and shape of the second discharging port 313. Forexample, when suction by a suction pump or supply of pressurized air bya pressure pump is performed on the ink tank 310, ink IK accumulated inthe main container 315 of the ink tank 310 is discharged from the seconddischarging port 313. The ink IK discharged from the second dischargingport 313 is guided in the +Z direction by the ink flow path 314, anddischarged from the discharging port 312 to the outside of the ink tank310. In this case, as illustrated in FIG. 9, detection processing of theproper ink amount can be performed by setting the positionalrelationship in which the ink flow path 314 and the photoelectricconversion device 322 do not face each other. For example, the ink flowpath 314 is provided at the end of the ink tank 310 in the −X direction,and the sensor unit 320 is provided in the +X direction from the inkflow path 314. In this way, the decrease in accuracy of the ink amountdetection processing can be suppressed by the ink in the ink flow path314.

As described above, the “discharging port” in the present embodimentincludes the discharging port 312 for discharging ink IK to the outsideof the ink tank 310, and the second discharging port 313 for dischargingink IK from the main container 315 to the discharging port 312. Amongthem, the second discharging port 313 is more strongly related towhether ink IK is supplied to the print head 107. As illustrated in FIG.9, the substrate 321 provided with the photoelectric conversion device322 is closer to the second discharging port 313 than the filling port311 of the ink tank 310. Thus, the ink amount detection processing canbe performed for a position where the ink amount is particularlyimportant. However, as the distance between the discharging port 312 andthe second discharging port 313 becomes longer, it is necessary tolengthen the ink flow path 314, and the arrangement of the ink flow path314 may become complicated. That is, it is desirable that thedischarging port 312 and the second discharging port 313 are provided atpositions close to each other. Therefore, as described above, byproviding the substrate 321 at a position closer to the discharging port312 than to the filling port 311, the ink amount detection processingcan be performed for a position where the ink amount becomes important.The same applies to the following description. In the expression that agiven member is “closer to the filling port 311 than to the dischargingport 312 of the ink tank 310” or similar expressions, the dischargingport 312 can be appropriately replaced with the second discharging port313.

The sensor unit 320 may be bonded to the ink tank 310, for example.Alternatively, the sensor unit 320 may be mounted on the ink tank 310 byproviding fixing members respectively to the sensor unit 320 and the inktank 310 and fixing the members by fitting or the like. Variousmodifications can be performed in the shape, material, or the like ofthe fixing member.

The photoelectric conversion device 322 is provided in the range of z1to z2, for example, in the Z-axis. The z1 and z2 are coordinate valuesin the Z-axis, and z1<z2. When the ink tank 310 is irradiated with lightfrom the light source 323, absorption and scattering of light occur bythe ink IK filled in the ink tank 310. Therefore, the portion of the inktank 310 not filled with the ink IK becomes relatively bright, and theportion filled with the ink IK becomes relatively dark. For example,when the interface of the ink IK exists at the position of thecoordinate value of z0 in the Z-axis, in the ink tank 310, the area ofthe Z coordinate value of z0 or less becomes dark and the area of the Zcoordinate value of greater than z0 becomes bright.

As illustrated in FIG. 9, the position of the interface of the ink IKcan be appropriately detected by providing the photoelectric conversiondevice 322 so that the longitudinal direction is the vertical direction.Specifically, in the case of z1<z0<z2, the photoelectric conversionelements arranged at a position corresponding to the range of z1 to z0out of the photoelectric conversion device 322 has a relatively smallamount of light to be inputted. Therefore, the output value becomesrelatively small. The photoelectric conversion elements arranged at aposition corresponding to the range of z0 to z2 has a relatively largeamount of light to be inputted, so that the output value becomesrelatively large. That is, z0 which is the interface of the ink IK canbe estimated based on the output of the photoelectric conversion device322. That is, it is possible to detect not only binary informationrelating to whether the ink amount is equal to or more than apredetermined amount but also a specific interface position. When theposition of the interface is known, the ink amount can be estimated inunits of milliliters or the like by preparing a conversion formula inadvance based on the shape of the ink tank 310. When the output value ofthe entire range of z1 to z2 is large, the interface can be determinedto be lower than z1, and when the output value of the entire range of z1to z2 is small, the interface can be determined to be higher than z2.The range where the ink amount can be detected is a range of z1 to z2which is a range where the photoelectric conversion device 322 isprovided. Therefore, the detection range can be easily adjusted bychanging the number of photoelectric conversion devices 322 and thelength per chip. The resolution of ink amount detection is determinedbased on the longer pitch between the pitch of the photoelectricconversion device 322 and the pitch of the lens array 325. For example,when photoelectric conversion elements of the photoelectric conversiondevice 322 are provided at intervals of 20 micrometers and lenses of thelens array 325 are provided at intervals of 300 micrometers, the inkamount detection is performed in units of 300 micrometers. The specificresolution can be variously modified. However, according to the methodof the present embodiment, it is possible to detect the ink amount withhigher accuracy than the related art.

In consideration of the accurate detection of the ink amount, it ispreferable that light emitted to the ink tank 310 be made to beapproximately the same degree regardless of the position in the verticaldirection. As described above, since whether the ink IK is presentappears as a difference in brightness, variation in light amount of theirradiation light leads to reduction in accuracy. Therefore, the sensorunit 320 has a light guide 324 disposed so that the longitudinaldirection is the vertical direction. The light guide 324 here is arod-shaped light guide as described above. In consideration of uniformlyilluminating the light guide, the light source 323 preferably causes thelight to enter the light guide from the longitudinal direction, that is,the direction along the longitudinal direction of the light guide. Sincethe incident angle becomes large in this way, total reflection is easilygenerated.

FIGS. 10 to 12 are diagrams for explaining the positional relationshipbetween the light source 323 and the light guide 324. For example, asillustrated in FIG. 10, the light source 323 and the light guide 324 maybe provided so as to be aligned in the Z-axis. The light source 323 canguide light in the longitudinal direction of the light guide 324 byemitting light in the +Z direction. Alternatively, as illustrated inFIG. 11, the end of the light guide 324 on the light source side may bebent. In this way, the light source 323 can guide light in thelongitudinal direction of the light guide 324 by emitting light in thedirection perpendicular to the substrate 321. Alternatively, asillustrated in FIG. 12, a reflective surface RS may be provided at theend of the light guide 324 on the light source side. The light source323 emits light in a direction perpendicular to the substrate 321. Lightfrom the light source 323 is guided in the longitudinal direction of thelight guide 324 by being reflected on the reflective surface RS. Thelight guide 324 according to the present embodiment can be widelyapplied to a known configuration such as providing a reflective plate onthe −Y direction surface of the light guide 324 and changing the densityof the reflective plate in accordance with the position from the lightsource 323. The light source 323 may be provided in the +Z directionfrom the light guide 324, or light sources 323 of the same color may beprovided at both ends of the light guide 324, or the configuration ofthe light source 323 and the light guide 324 may be variously modified.

It is desirable that at least a portion of the inner wall of the inktank 310 that faces the photoelectric conversion device 322 is higher inink repellency than the outer wall of the ink tank 310. Of course, theentire inner wall of the ink tank 310 may be processed to enhance theink repellency in comparison with the outer wall of the ink tank 310.The portion facing the photoelectric conversion device 322 may be theentire inner wall in the −Y direction of the ink tank 310 or a portionof the inner wall. Specifically, in the inner walls of the ink tank 310in the −Y direction, the portion of the inner wall is an area includinga portion where the position on the XZ plane overlaps the photoelectricconversion device 322. As will be described later with reference to FIG.33, when an ink droplet adheres to the inner wall of the ink tank 310,the portion of the ink droplet becomes darker than a portion where noink is present. Therefore, there is a possibility that the ink amountdetection accuracy may be lowered due to the ink droplet. By enhancingthe ink repellency of the inner wall of the ink tank 310, the adhesionof ink droplets can be suppressed.

1.6 Detailed Configuration Example of Sensor Unit and Processing Unit

FIG. 13 is a functional block diagram relating to the sensor unit 320.The electronic apparatus 10 includes a second substrate 111 providedwith the processing unit 120 and an analog front end (AFE) 130. Theprocessing unit 120 outputs a control signal for controlling thephotoelectric conversion device 322 corresponding to the processing unit120 illustrated in FIG. 5. The control signal includes a clock signalCLK and a chip enable signal EN1 described later. The AFE 130 is acircuit having at least a function of analog-to-digital (A/D) convertingan analog signal from the photoelectric conversion device 322. Thesecond substrate 111 is, for example, a main substrate of the electronicapparatus 10, and the substrate 321 is a sub-substrate for a sensorunit.

In FIG. 13, the sensor unit 320 includes a red LED 323R, a green LED323G, a blue LED 323B, and n photoelectric conversion devices 322. Asdescribed above, n is an integer of 1 or more. The red LED 323R, thegreen LED 323G, and the blue LED 323B are provided in the light source323, and a plurality of photoelectric conversion devices 322 arearranged on the substrate 321. A plurality of red LEDs 323R, green LEDs323G, and blue LEDs 323B may exist, respectively. The AFE 130 isrealized by, for example, an integrated circuit (IC).

The processing unit 120 controls the operation of the sensor unit 320.First, a processing unit 120 controls operations of the red LED 323R,the green LED 323G, and the blue LED 323B. Specifically, the processingunit 120 supplies a drive signal DrvR to the red LED 323R at a fixedperiod T for a fixed exposure time Δt and causes the red LED 323R toemit light. Similarly, the processing unit 120 supplies the green LED323G with a drive signal DrvG for the exposure time Δt at the period Tto cause the green LED 323G to emit light, and supplies the blue LED323B with a drive signal DrvB for the exposure time Δt at the period Tto cause the blue LED 323B to emit light. The processing unit 120 causesthe red LED 323R, the green LED 323G, and the blue LED 323B to emitlight one or more times exclusively one by one in order during theperiod T.

The processing unit 120 controls the operation of the n photoelectricconversion devices 322-1 to 322-n. Specifically, the processing unit 120supplies the clock signals CLK in common to the n photoelectricconversion devices 322. The clock signal CLK is an operation clocksignal of the n photoelectric conversion devices 322, and each of the nphotoelectric conversion devices 322 operates based on the clock signalCLK.

Each photoelectric conversion device 322-j (j=1 to n) generates andoutputs a signal OS based on light received by each light receivingelement in synchronization with the clock signal CLK when receiving achip enable signal ENj after the light receiving element receives light.

The processing unit 120 causes the red LED 323R, the green LED 323G, orthe blue LED 323B to emit light, generates a chip enable signal EN1 thatis active only until the photoelectric conversion device 322-1 finishesoutputting the output signal OS, and supplies it to the photoelectricconversion device 322-1.

The photoelectric conversion device 322-j generates a chip enable signalENj+1 before the output of the output signal OS is finished. The chipenable signals EN2 to ENn are supplied to photoelectric conversiondevices 322-2 to 322-n, respectively.

Thus, after the red LED 323R, the green LED 323G, or the blue LED 323Bemits light, the n photoelectric conversion devices 322 sequentiallyoutput the output signals OS. Then, the sensor unit 320 outputs theoutput signal OS sequentially output by the n photoelectric conversiondevices 322 from a terminal (not illustrated). The output signal OS istransferred to the second substrate 111 through wiring (not illustrated)that electrically couples the sensor unit 320 and the second substrate111.

The AFE 130 sequentially receives the output signals OS outputted inorder from the n photoelectric conversion devices 322, performsamplification processing and A/D conversion processing with respect toeach output signal OS to convert into digital data including a digitalvalue corresponding to the amount of light received by each lightreceiving element, and sequentially transmits each digital data to theprocessing unit 120. The processing unit 120 receives each digital datasequentially transmitted from the AFE 130, and performs ink amountdetection processing and ink characteristics determination processingdescribed later. The processing unit 120 may perform correctionprocessing using a first correction parameter or the like describedlater, before the ink amount detection processing or the like.

FIG. 14 is a functional block diagram of the photoelectric conversiondevice 322. The photoelectric conversion device 322 is provided with acontrol circuit 3222, a boosting circuit 3223, a pixel drive circuit3224, p pixel units 3225, a correlated double sampling (CDS) circuit3226, a sample hold circuit 3227, and an output circuit 3228. Thephotoelectric conversion device 322 is supplied with a power supplyvoltage VDD and a power supply voltage VSS from the two power supplyterminals VDP and VSP, respectively. The photoelectric conversion device322 operates based on a chip enable signal EN_I, a clock signal CLK, anda reference voltage VREF supplied from a reference voltage supplyterminal VRP. The power supply voltage VDD corresponds to a highpotential side power supply, and is 3.3 V, for example. The VSScorresponds to a low potential side power supply, and is 0 V, forexample. The chip enable signal EN_I is any one of chip enable signalsEN1 to ENn in FIG. 13.

The chip enable signal EN_I and the clock signal CLK are inputted to thecontrol circuit 3222. The control circuit 3222 controls operations ofthe boosting circuit 3223, the pixel drive circuit 3224, the p pixelunits 3225, the CDS circuit 3226, and the sample hold circuit 3227 basedon the chip enable signal EN_I and the clock signal CLK. Specifically,the control circuit 3222 generates a control signal CPC that controlsthe boosting circuit 3223, a control signal DRC that controls the pixeldrive circuit 3224, a control signal CDSC that controls the CDS circuit3226, a sampling signal SMP that controls the sample hold circuit 3227,a pixel selection signal SELO that controls the pixel unit 3225, a resetsignal RST, and a chip enable signal EN_O.

The boosting circuit 3223 boosts the power supply voltage VDD based onthe control signal CPC from the control circuit 3222, and generates atransfer control signal Tx that sets the boosted power supply voltage toa high level. The transfer control signal Tx is a control signal fortransferring electric charges generated during exposure time Δt based onphotoelectric conversion by the light receiving element and is commonlysupplied to the p pixel units 3225.

The pixel drive circuit 3224 generates a drive signal Dry for drivingthe p pixel units 3225 based on the control signal DRC from the controlcircuit 3222. The p pixel units 3225 are arranged side by side in aone-dimensional direction, and the drive signal Dry is transferred tothe p pixel units 3225. When the drive signal Dry is active and a pixelselection signal SELi−1 is active, an i-th, i being any one of 1 to p,pixel unit 3225 activates a pixel selection signal SELi and outputs asignal. The pixel selection signal SELi is outputted to an i+1th pixelunit 3225.

The p pixel units 3225 include photoelectric conversion elements thatreceive light and perform photoelectric conversion, and based on thetransfer control signal Tx, the pixel selection signal SEL (any one ofSELO to SELp−1), the reset signal RST, and the drive signal Dry,respectively, output a signal having a voltage corresponding to lightreceived by the light receiving element during the exposure time Δt.Signals outputted from the p pixel units 3225 are sequentiallytransferred to the CDS circuit 3226.

The CDS circuit 3226 receives a signal Vo sequentially including thesignals respectively output from the p pixel units 3225, and operatesbased on the control signal CDSC from the control circuit 3222. The CDScircuit 3226 removes noise generated by the characteristics variation inthe amplification transistors of the p pixel units 3225 and superimposedon the signal Vo by correlated double sampling with the referencevoltage VREF as a reference. That is, the CDS circuit 3226 is a noisereduction circuit for reducing noise included in the signals outputtedfrom the p pixel units 3225.

The sample hold circuit 3227 samples the signal from which noise isremoved by the CDS circuit 3226 based on the sampling signal SMP, holdsthe sampled signal, and outputs it to the output circuit 3228.

The output circuit 3228 amplifies the signal outputted from the samplehold circuit 3227 to generate the signal OS. As described above, thesignal OS is outputted from the photoelectric conversion device 322 viaan output terminal OP1 and supplied to the AFE 130.

The control circuit 3222 generates a chip enable signal EN_O which is ahigh pulse signal shortly before the output of the signal OS from theoutput circuit 3228 is finished, and outputs it from an output terminalOP2 to a next-stage photoelectric conversion device 322. The chip enablesignal EN_O here is any one of chip enable signals EN2 to ENn+1 in FIG.13. Thereafter, the control circuit 3222 causes the output circuit 3228to stop outputting the signal OS and sets the output terminal OP1 tohigh impedance.

As described above, the electronic apparatus 10 according to the presentembodiment is a printer, and the printer includes the ink tank 310, theprint head 107, the substrate 321, the light source 323, thephotoelectric conversion device 322, and the processing unit 120. Theprint head 107 performs printing by using ink IK in the ink tank 310.The light source 323 is provided on the substrate 321 and irradiates theink tank 310 with light from the side of the ink tank 310. The side isspecifically the horizontal direction and includes both the directionalong the X-axis and the direction along the Y-axis. In the presentembodiment, light is emitted from the direction along the Y-axis. Thephotoelectric conversion device 322 is provided on the substrate 321 anddetects light incident from the ink tank in a period during which thelight source 323 emits light. The processing unit 120 detects the amountof ink in the ink tank 310 based on the output of the photoelectricconversion device 322. In this way, the amount of ink in the ink tank310 can be detected by using the light source 323 and the photoelectricconversion device 322 provided on the same substrate 321. The sensorunit 320 including the light source 323 and the photoelectric conversiondevice 322 can be integrally configured, and the arrangement is easilyoptimized.

2. Modifications related to Configuration of Electronic Apparatus

The configuration of the electronic apparatus 10 is not limited to thatdescribed above, and various modifications can be made for each portion.

2.1 Window Portion

The electronic apparatus 10 may include ink viewing window portions 103in the ink tank 310. For example, the case 301 is provided with thewindow portions 103 corresponding to each of the five ink tanks 310. Thewindow portions 103 may be opening portions formed in the case 301, ormay be a light transmissive member. The user can visually recognize thefive ink tanks 310 through the window portions 103.

FIG. 15 is a perspective diagram of the electronic apparatus 10including the window portions 103. In the example illustrated in FIG.15, the window portions 103 are provided on a surface in the +Ydirection that is the front side of the case 301 of the ink tank unit300. By providing the window portions 103, the user can visuallyrecognize a portion of the side surface of the ink tank 310 in the +Ydirection, specifically a portion of the ink tank 310 facing the windowportion 103.

Further, a portion of each ink tank 310 facing the window portion 103has light transmittance. Therefore, the user can visually recognize theamount of ink IK included in the ink tank 310 through the window portion103. The window portion 103 which is a member having light transmittancemay be provided with a scale. The user can grasp the amount of ink IK ineach ink tank 310 by using the scale as a mark. The scale may beprovided on the side surface of the ink tank 310 instead of the windowportion 103.

As can be seen from FIGS. 9 and 15, the window portion 103 is closer tothe filling port 311 than to the discharging port 312 of the ink tank310. In other words, the window portion 103, the filling port 311, andthe discharging port 312 are arranged in this order along the −Ydirection. As described above with reference to FIG. 9, the sensor unit320 is provided at a position closer to the discharging port 312 than tothe filling port 311 of the ink tank 310. That is, when the ink tank 310is used as a reference, the window portion 103 is positioned in the +Ydirection, and the sensor unit 320 is positioned in the −Y direction.Thus, it is possible to suppress the visual recognition of the inkamount by the user from being hindered by the sensor unit 320, and toefficiently arrange each part of the electronic apparatus 10.

2.2 Modifications related to Optical Separator

As illustrated in FIG. 9, in the method of the present embodiment, theamount of ink is detected by arranging the linear image sensors in thevertical direction. In the ink amount detection processing, eachphotoelectric conversion element included in the photoelectricconversion device 322 is required to detect light from a position facingthe ink tank 310 in the Z direction. For example, it is desirable thatthe photoelectric conversion element provided at a position where the Zcoordinate value is z3 mainly detects light from a position where the Zcoordinate value is z3 in the ink tank 310, which is ideal. In otherwords, when the photoelectric conversion element provided at theposition where the Z coordinate value is z3 detects light from aposition where the Z coordinate value is not z3, the detection accuracymay be reduced. Therefore, the sensor unit 320 desirably includes anoptical separator for separating light in the vertical direction.

FIG. 16 is a schematic diagram illustrating the relationship between theink tank 310, the optical separator, and the photoelectric conversiondevice 322 when the lens array 325 is included as the optical separatoras in the example illustrated in FIG. 6. In FIG. 16, the shape of theink tank 310 is simplified. From this point onward, the description ofthe drawings is simplified with respect to the portion of the ink tank310 that does not require a detailed shape. The drawing is an example inwhich the lower end of the photoelectric conversion device 322 islocated below the lower end of an ink chamber of the ink tank 310 sothat the ink amount can be detected until the ink almost runs out.Although the lower end of the ink tank 310 and the lower end of thephotoelectric conversion device 322 have substantially the same heightin the drawing, the lower end of the photoelectric conversion device 322may be positioned further below the lower end of the ink tank 310.

Each lens included in the lens array 325 collects light incident on thelens at a predetermined position. Therefore, each photoelectricconversion element included in the photoelectric conversion device 322mainly receives light transmitted through a given lens and alsosuppresses reception of light transmitted through another lens. Forexample, the photoelectric conversion element provided in the rangeillustrated by A0 mainly receives light from the lens illustrated by A1and suppresses reception of light from the lens provided A2 and the lensprovided in the −Z direction from A2. By using the lens array 325, sincelight is separated in the vertical direction, the accuracy of ink amountdetection can be improved.

However, although the method of the present embodiment can use a linearimage sensor the same as that in the image reading in the scanner unit200, the ink amount detection processing does not necessarily requirethe same accuracy as in the image reading processing. When the inkamount detection processing requires lower accuracy, it is possible touse a simple optical separator having a light separation performancelower than that of the lens array 325.

FIG. 17 is a schematic diagram for explaining another example of theoptical separator. As illustrated in FIG. 17, the optical separator maybe an optical slit provided between the photoelectric conversion device322 and the ink tank 310. The optical slit is, for example, a resin slit330 formed of a resin material.

Slits are formed by alternately providing areas having relatively highlight transmittance and areas having relatively low light transmittancein the Z-axis. The area having high light transmittance and the areahaving low light transmittance are areas having a width of severalhundred micrometers in the Z-axis respectively, for example. The resinslit 330 may be provided in the case 326 of the sensor unit 320. Amember having low light transmittance is used for the case 326 forsuppressing the incidence of environmental light to the photoelectricconversion device 322. Therefore, the resin slit 330 can be formed byproviding the case 326 with openings having a pitch of several hundredmicrometers. For example, in FIG. 6, the second opening portion 328 isillustrated as one continuous opening in a given range of the Z-axis,the resin slit 330 is realized by changing this to a plurality ofopenings provided at intervals of several hundred micrometers within agiven range of the Z-axis. The area having high light transmittance isnot limited to the opening, and may be formed of a light transmittingmember having higher light transmittance than that of the case 326. Theresin slit 330 illustrated in FIG. 17 is not limited to the one formedin the case 326, and may be provided as a separate body from the case326. For example, the resin slit 330 separated from the case 326 isprovided at a position corresponding to the lens array 325 in FIG. 6 orFIG. 8.

Among a plurality of photoelectric conversion elements included in thephotoelectric conversion device 322, a photoelectric conversion elementcorresponding to an area with high light transmittance detects lightfrom the ink tank 310. On the other hand, among the plurality ofphotoelectric conversion elements included in the photoelectricconversion device 322, a photoelectric conversion element correspondingto an area with low light transmittance has very little incidence oflight from the ink tank 310. In order to suppress misidentifying an areawhere light is not incident due to the optical separator as an areawhere the ink IK exists, in the ink amount detection processing and thelike to be described later, processing of extracting a portioncorresponding to an area having a high light transmittance from a signaloutput from the photoelectric conversion device 322 is performed. Forexample, since the pitch of the resin slit 330 is known in design, theprocessing unit 120 extracts data corresponding to the opening portionof the slit from the signal OS as a set of output data of a plurality ofphotoelectric conversion elements, and performs ink amount detectionprocessing based on data after the extraction processing. For example, awaveform described later with reference to FIG. 31 is data after theextraction processing.

The optical separator may be provided on the side surface of the inktank 310. In this case, the electronic apparatus 10 includes the inktank 310 provided with an optical separator that separates light in thevertical direction on the side surface, the print head 107 that performsprinting by using ink IK in the ink tank 310, the photoelectricconversion device 322 that detects light incident from the ink tank 310through the optical separator, and the processing unit 120 that detectsthe amount of ink in the ink tank 310 based on the output of thephotoelectric conversion device 322. As described above, by providingthe optical separator on the side surface of the ink tank 310, theconfiguration on the sensor unit 320 side can be simplified.Specifically, since the lens array 325 illustrated in FIG. 16 and theresin slit 330 illustrated in FIG. 17 can be omitted, the sensor unit320 can be miniaturized.

FIG. 18 is a schematic diagram for explaining the optical separatorprovided on the side surface of the ink tank 310. The optical separatoris an optical slit. This makes it possible to separate light in thevertical direction by using the slits provided in the ink tank 310.

The optical separator separates light in a vertical direction by passingthe first light through a first transmission area between the firstlayer and the second layer and passing the second light through a secondtransmission area between the second layer and the third layer. Thelayer here represents any one of the structures in which a plurality oflayers overlap each other in a predetermined direction. In this way, anoptical slit can be formed by sandwiching an area having relatively highlight transmittance by two layers having relatively low lighttransmittance. Since the ink tank 310 needs to accommodate ink IK whichis a liquid, it is necessary to use a light transmissive member insteadof an opening in an area where the light transmittance is relativelyhigh. Various specific methods for forming layers are conceivable.

FIG. 19 is a schematic diagram illustrating a configuration of the inktank 310 having the optical slits on the side surface. FIG. 19illustrates a configuration of a side surface of the ink tank 310 in the−Y direction. The optical separator is formed by coating the outer wallof the ink tank 310 having light transmittance with a member having lowlight transmittance. Thus, the first layer, the second layer, and thethird layer of the optical separator are coating layers. The coatinglayers are stacked in the −Y direction with respect to the outer wall ofthe ink tank 310. That is, in the configuration illustrated in FIG. 19,the ink tank 310 and the coating layers are stacked along the Y-axis.The thickness in the Y-axis is emphasized in FIG. 19, but the coatinglayers can be formed very thin. The second layer is a coating layeradjacent to the first layer in the Z-axis, and the third layer is acoating layer adjacent to the second layer in the Z-axis. For example,B1 in FIG. 19 is a first layer, B2 is a second layer, B3 is a thirdlayer, B4 is a first transmission area, and B5 is a second transmissionarea.

Since the coating layers are easy to form, the pitch of the opticalseparator can be narrowed. For example, when the resin slits 330illustrated in FIG. 17 or two-color molding described later is used, thepitch of the optical separator is on the order of several hundredsmicrometers to several millimeters, which is a factor that makes itimpossible to increase the resolution of ink amount detection. In thisregard, it is considered that the ink amount can be detected with aresolution of the order of several tens of micrometers by using thecoating layers.

The area where the light transmittance is relatively low is not limitedto the coating layer. The first layer, the second layer, and the thirdlayer are layers of one color of two-color molding, and the firsttransmission area and the second transmission area may be layers of theother color of two-color molding. A member having low lighttransmittance constituting the first to third layers is described as afirst member and a member having high light transmittance constitutingthe first transmission area and the second transmission area isdescribed as a second member of two members used for the two-colormolding. Thus, the ink tank 310 having the optical separator on the sidesurface can be formed by using two-color molding using the two membershaving different light transmittances.

FIGS. 20 and 21 are schematic diagrams illustrating the configuration ofthe ink tank 310 in which the optical slits are provided on the sidesurface by two-color molding. The structure in the XZ plane is the sameas the example in FIG. 19 which uses the coating layer. However, variousconfigurations in the YZ plane are conceivable.

For example, as illustrated in FIG. 20, the first to third layers may beformed on the surface portion of the ink tank 310. That is, the secondmember and the first member are laminated along the Y-axis as indicatedby C1, and the first member does not penetrate the side surface of theink tank 310 on the Y-axis. In FIG. 20, the first to third layers may beconsidered to be layers stacked on the Z-axis. Specifically, the firstmember and the second member are alternately stacked in the directionindicated by C2 in FIG. 20.

Alternatively, as illustrated in FIG. 21, the first member may beprovided so as to penetrate the side surface of the ink tank 310 on theY-axis. The first member and the second member are alternately stackedon the Z-axis in FIG. 21.

As described above with reference to FIG. 4, the ink tank 310 includesthe filling port 311 into which ink IK is filled by the user and thedischarging port 312 for discharging the ink IK toward the print head107. The optical separator is provided on the side surface of the inktank 310 in the −Y direction closer to the discharging port 312 than tothe filling port 311. Thus, light directing from the ink tank 310 to thephotoelectric conversion device 322 can be separated in the verticaldirection.

In addition, although the example in which the optical separator is aslit has been described above, the present disclosure is not limitedthereto, and other configurations capable of separating light in thevertical direction may be used. Specifically, the optical separator maybe an optical pinhole. In FIGS. 19 to 21, the first layer and the secondlayer are rectangles having the ±X direction as the longitudinaldirection and the ±Z direction as the short side direction in the XZplane, and the first transmission area is an area between the firstlayer and the second layer. When the optical pinhole is used, the firsttransmission area may be formed into a minute circular shape, and thefirst layer may be provided in the +Z direction and the second layer maybe provided in the −Z direction so as to surround the circular shape. Inthis case, the first layer and the second layer are continuous atpositions deviated from the pinhole in the X direction or the −Xdirection.

As described above, the photoelectric conversion device 322 has aplurality of photoelectric conversion elements. The arrangement pitch ofthe plurality of photoelectric conversion elements is narrower than thepitch of the optical separation by the optical separator. Thearrangement pitch of the photoelectric conversion elements is aninterval at which the photoelectric conversion elements are provided.The optical separation pitch is an interval between members having lowlight transmittance or an interval between members having high lighttransmittance. For example, the optical separation pitch is an intervalbetween the first layer and the second layer or an interval between thefirst transmission area and the second transmission area.

When the resin slit 330 illustrated in FIG. 17 and the two-color moldingillustrated in FIGS. 20 and 21 are used, it is not easy to form theminute structure and it is difficult to narrow the optical separationpitch. Further, it is not necessary to narrow the optical separationpitch than a pitch of the photoelectric conversion elements. Forexample, when the light separation pitch is narrow enough to allow bothlight transmitted through the first transmission area and light from thesecond transmission area to enter one photoelectric conversion element,the significance of light separation by the second layer is damaged.

Furthermore, a signal value of the photoelectric conversion element islowered when light is blocked by the second layer. That is, by makingthe arrangement pitch of the plurality of photoelectric conversionelements narrower than the optical separation pitch by the opticalseparator, the formation of the optical separator is facilitated and theefficient configuration can be realized.

Further, the example of providing an optical separator on one of theside surfaces of the sensor unit 320 and the ink tank 310 has beendescribed above. However, when the ink amount detection processing doesnot require accuracy compared to the image reading processing in thescanner unit 200, the optical separator can be omitted. FIG. 22 is aschematic diagram describing the relationship between the photoelectricconversion device 322 and the ink tank 310 when the optical separator isomitted.

2.3 Modifications Related to Light Source

2.3.1 Relationship with Light Guide

In the example illustrated in FIG. 6, the sensor unit 320 includes thelight guide 324. The light source 323 irradiates the light guide 324with light. As described above, in order to make the light guide 324emit light uniformly, light from the light source 323 needs to beincident in a direction along the longitudinal direction of the lightguide 324. Specific methods can be considered in various ways asillustrated in FIGS. 10 to 12. In the examples illustrated in FIGS. 10to 12, the position of the light source 323 in the Z-axis does notoverlap the photoelectric conversion device 322. However, therelationship between the light guide 324 and the light source 323 is notlimited thereto.

FIGS. 23 and 24 are schematic diagrams illustrating other configurationsof the light source 323 and the light guide 324. As illustrated in FIG.23, the light source 323 may irradiate the light guide 324 with lightfrom a direction intersecting the longitudinal direction of the lightguide 324. The longitudinal direction of the light guide 324 is adirection along the longitudinal direction of the photoelectricconversion device 322 and a direction along the Z-axis. The light source323 is provided in the −Y direction with respect to the light guide 324,and emits light in the +Y direction. More preferably, the light source323 is provided near the center of the light guide 324 in the Z-axis.For example, as illustrated in FIG. 24, the photoelectric conversiondevice 322 and the light guide 324 are provided in the same range on theZ-axis, and the light source 323 is disposed at the center of the range.

When the configuration illustrated in FIG. 23 is used, light from thelight source 323 is less likely to propagate inside the light guide 324as compared with FIGS. 10 to 12. It is because that, in theconfiguration in FIG. 23, an incident angle when light enters aninterface from an inside to an outside of the light guide 324 is smalland total reflection is difficult to occur. Therefore, the lightincident on the light guide 324 is emitted in the +Y direction beforesufficiently propagating inside the light guide 324. As a result, thelight emitted from the light guide 324 toward the ink tank 310 is morelikely to cause intensity variation in the Z-axis than in theconfigurations of FIGS. 10 to 12.

In the scanner unit 200, the image sensor needs to read an image of adocument of a predetermined size, for example, A4 size or A3 size, sothat a certain length is required in the longitudinal direction.Therefore, in the scanner unit 200, it is required to emit lightuniformly over a wide range to some extent. On the other hand, thephotoelectric conversion device 322 of the present embodiment is usedfor detecting the ink amount and does not require a length in comparisonwith the scanner unit 200. This is because there are many cases wherethe side surface of the ink tank 310 itself is not so long in thevertical direction, and the ink amount may be detected only in a portionof the side surface. For example, in the case of detecting an ink end oran ink near end, a problem hardly occurs even if only a range of severalcentimeters close to the bottom surface of the ink tank 310 is an objectof the ink amount detection. The ink end represents a state where theamount of ink is small and it is difficult to continue printing, and theink near end is a state in which it is determined that printing can becontinued but the amount of ink is small.

When the photoelectric conversion device 322 is short, since the area tobe irradiated with light is also shortened, the light guide 324 can beshortened accordingly. Therefore, even if the light source 323 isdisposed in a positional relationship in which total reflection is hardto occur, since an area of a sufficient proportion of the light guide324 emits light, accuracy deterioration caused by unevenness ofluminance hardly occurs. That is, even if the configurations of FIGS. 23and 24 are used, the ink amount can be detected with sufficientaccuracy. In this case, since processing of bending the light guide 324as illustrated in FIG. 11 and processing of providing a reflectivesurface RS as illustrated in FIG. 12 become unnecessary, mounting isfacilitated. The light source 323 is disposed in the horizontaldirection with respect to the photoelectric conversion device 322. Thehorizontal direction here is specifically the +X direction or the −Xdirection. In other words, the positions of the light source 323 and thephotoelectric conversion device 322 in the Z-axis overlap each other.That is, unlike the example illustrated in FIG. 10, it is not necessaryto arrange the light guide 324 and the light source 323 in thelongitudinal direction, and the size of the substrate 321 and the sensorunit 320 in the vertical direction can be reduced.

The light guide 324 may be omitted from the sensor unit 320. In thiscase, the light source 323 is disposed at a position illustrated in FIG.24, for example, and the light guide 324 is omitted in FIG. 24. Lightfrom the light source 323 passes through the first opening portion 327of the case 326 and is emitted to the ink tank 310. In this case, thelight emitted to the ink tank 310 is likely to have uneven brightness onthe Z-axis. However, as described above, when the photoelectricconversion device 322 is short, ink detection may be performed withsufficient accuracy even if the light guide 324 is omitted.

As described above, in the example when the light source 323 and thephotoelectric conversion device 322 are provided on the same substrate321, various modifications can be performed for the configuration of theoptical separator and the configuration of the light guide 324. Forexample, when accuracy is important, the configuration in which the lensarray 325 is provided as the optical separator, and the light source 323and the light guide 324 are likely to generate total reflection asillustrated in FIGS. 10 to 12 is used. When it is important to simplifythe configuration, both the optical separator and the light guide 324are omitted. In addition, various modifications can be implemented forspecific combinations such as omitting the light guide 324 and providingthe optical separator.

2.3.2 Location of Light Source

The light source 323 and the photoelectric conversion device 322 are notlimited to those arranged on the same substrate. FIG. 25 is anotherdiagram for explaining the positional relationship between the lightsource 323, the photoelectric conversion device 322, and the ink tank310. As illustrated in FIG. 25, the photoelectric conversion device 322may be provided in a given direction with respect to the ink tank 310,and the light source 323 may be provided in an opposite direction fromthe given direction. In the example illustrated in FIG. 25, thephotoelectric conversion device 322 is provided on the side surface ofthe ink tank 310 in the −Y direction, and the light source 323 isprovided on the side surface of the ink tank 310 in the +Y direction. Inthe example illustrated in FIG. 9, the photoelectric conversion device322 detects reflected light of light emitted from the light source 323in the ink tank 310, but in the example illustrated in FIG. 25, thephotoelectric conversion device 322 detects transmitted light that isemitted from the light source 323 and transmitted through the ink tank310.

FIG. 26 is an exploded diagram illustrating the configuration of thelight receiving unit 340 including the photoelectric conversion device322. The light receiving unit 340 includes a sensor substrate 341, thephotoelectric conversion device 322, the lens array 325 as the opticalseparator, and a sensor case 342. FIG. 27 is an exploded diagramillustrating the configuration of a light emitting unit 350 includingthe light source 323. The light emitting unit 350 includes a lightsource substrate 351, the light source 323, the light guide 324, and alight source case 352. In FIGS. 26 and 27, the same components as thosein FIG. 6 are denoted by the same reference numerals. As can be seenfrom FIGS. 26 and 27, the light receiving unit 340 has a configurationin which a portion of the sensor unit 320 in FIG. 6 is extracted, andthe light emitting unit 350 has a configuration in which the remainingportion of the sensor unit 320 is extracted. In the case of theconfigurations illustrated in FIGS. 26 and 27, since direct light fromthe light source 323 to the photoelectric conversion device 322 is notrequired to be taken into consideration, it is not necessary to providea light shielding wall.

As illustrated in FIGS. 16 to 22, modifications such as changing thelens array 325 to the resin slit 330, providing an optical separator onthe side surface of the ink tank 310, and omitting the optical separatorcan be executed. Further, as described above with reference to FIGS. 23and 24, modifications such as changing the positional relationshipbetween the light source 323 and the light guide 324 and omitting thelight guide 324 can be executed.

The light receiving unit 340 in FIG. 26 and the light emitting unit 350in FIG. 27 are respectively arranged on different side surfaces of theink tank 310 as illustrated in FIG. 25. By aligning positions of thelight receiving unit 340 and the light emitting unit 350 in the Z-axisand X-axis, ink amount detection using transmitted light becomespossible. Even in the case of using the transmitted light, since thetransmitted light easily reaches the photoelectric conversion device 322in the area where the ink IK does not exist, the output value of thephotoelectric conversion element corresponding to the area increases.Since absorption and scattering of light in the ink IK occur in the areawhere the ink IK exists, transmitted light reaching the photoelectricconversion device 322 is weak and the output value of the photoelectricconversion element corresponding to the area is small. Therefore, evenin the configuration of FIG. 25, the ink amount can be detected by thesame method as in FIG. 9. Specific processing is described later.

FIG. 28 is another diagram for explaining the positional relationshipbetween the light source 323, the photoelectric conversion device 322,and the ink tank 310. The photoelectric conversion device 322 and theink tank 310 are the same as those in FIG. 25. That is, the lightreceiving unit 340 illustrated in FIG. 26 is provided on the sidesurface of the ink tank 310 in the −Y direction. FIG. 28 illustrates anexample of providing the light source 323 on the upper surface of theink tank 310. However, the light source 323 can be provided at anoptional position when the light source 323 is at a position capable ofirradiating the inside of the ink tank 310 with light. In FIG. 28, thesubstrate provided with the light source 323 is omitted. In FIG. 28,although the provision of the light guide 324 and the light source case352 is not hindered, these can be omitted.

The light source 323 irradiates the inside of the ink tank 310 withlight. When a certain amount of light enters the inside of the ink tank310, reflection occurs at the inner wall of the ink tank 310 and theinterface of the ink IK, and the entire inside of the ink tank 310 emitslight. Hereinafter, light illuminating the entire inside of the ink tank310 is described as spatial light. By using the spatial light, even ifthe positional relationship between the light emitting side and thelight receiving side is not exactly aligned as illustrated in FIG. 9 orFIG. 25, it is possible to realize a state where the area where the inkIK does not exist becomes bright and the area where the ink IK existsbecomes dark. When spatial light emitted from the side surface of theink tank 310 is detected by using the photoelectric conversion device322, the output value of the photoelectric conversion element changes inaccordance with whether ink is present. Therefore, the ink amount can bedetected by the same method as in FIG. 9 or FIG. 25.

The configuration illustrated in FIG. 28 has an advantage that thedegree of freedom of the position of the light source 323 is high. Onthe other hand, since the irradiation direction of light from the lightsource 323 cannot be limited in the configuration illustrated in FIG.28, the amount of light incident on the photoelectric conversion device322 is considered to be small as compared to the configuration of FIG. 9or FIG. 25. Therefore, it is considered that the ink amount detectionaccuracy is higher by using the configuration of FIG. 9 or FIG. 25 thanby using the configuration of FIG. 28.

2.3.3 Type of Light Source

In the above, three of the red LED 323R, the green LED 323G, and theblue LED 323B are provided as the light source 323, and an example inwhich these emit light sequentially has been illustrated. In this case,the photoelectric conversion device 322 sequentially outputs a signalcorresponding to red, a signal corresponding to green, and a signalcorresponding to blue. However, the type and the number of light sources323 are not limited thereto.

For example, the light source 323 may be a white LED. The white LED maybe realized by a method of mixing each light of the red LED 323R, thegreen LED 323G, and the blue LED 323B. Alternatively, the white LED maybe realized by a method of combining the LED of a given wavelength bandand a phosphor. For example, the white LED can be realized by combininga blue LED and a yellow phosphor, and combining a blue LED, and a redphosphor and a green phosphor.

Light emitted from the light source 323 is not limited to the wavelengthband of visible light. For example, the electronic apparatus 10 includesthe light source 323 that irradiates the ink tank 310 with infraredlight. The light source 323 that emits infrared light may be an LED orother light sources. Hereinafter, it is assumed that the light source323 that emits infrared light is an LED, and the LED is referred to asan infrared LED. The photoelectric conversion device 322 detects lightbased on infrared light emitted from the light source 323 to the inktank 310. The light source 323 that emits infrared light has highaffinity with the ink viewing window portion 103 in the ink tank 310.

The window portion 103 has light transmittance for visually recognizingink IK by the user. Therefore, when the light source 323 that emitsvisible light is used, the light from the light source 323 may bevisually recognized by the user. When the light emitted from the lightsource 323 is visually recognized every time ink amount is detected, itis troublesome for the user and there is a possibility that the use ofthe electronic apparatus 10 is hindered. In that respect, when the lightsource 323 that emits infrared light is used, since the light emittedfrom the light source 323 is not visually recognized by the user, it ispossible to suppress discomfort to the user. The light source 323 thatemits ultraviolet light may be used. However, it is preferable to useinfrared light having a low frequency in consideration of thedeterioration of the ink IK due to the light energy.

Even when infrared light is used, as in the example illustrated in FIGS.9 and 15, the photoelectric conversion device 322 is provided on theside surface among the side surfaces of the ink tank 310 in the −Ydirection that is the horizontal direction, and the window portion 103is provided in the +Y direction, which is the opposite direction fromthe −Y direction, with respect to the ink tank 310. In this way, thevisual recognition of the ink IK by the user can be suppressed frombeing hindered by the photoelectric conversion device 322.

The thing that ink tank 310 includes the filling port 311 and thedischarging port 312, the window portion 103 is closer to the fillingport 311 than to the discharging port 312, and the photoelectricconversion device 322 is closer to the discharging port 312 than to thefilling port 311 are the same as the above-described example.

Heretofore, five of red LED, green LED, blue LED, white LED, andinfrared LED have been exemplified. The light source 323 may be one ofthese or a combination of two or more. When a plurality of light sourcesare used, it is not always necessary to use all the light sources. Inthis case, it is desirable to use the infrared LED with a frequencyhigher than that of the light source generating visible light so as notto be visible to the user as much as possible. For example, all thelight sources are used immediately after the power source is turned onor the ink is replenished, but only the infrared LED may be used in thesubsequent normal state to avoid the use of other light sourcesgenerating visible light. Further, the light source 323 is not limitedto the LED, and may be a light source using other methods such as axenon lamp, a semiconductor laser, or the like.

Further, the method for detecting a plurality of light beams havingdifferent wavelength bands in the photoelectric conversion device 322 isnot limited to those using a plurality of LEDs. For example, the sensorunit 320 may include a light source 323 having a wide wavelength bandand a filter (not illustrated). The photoelectric conversion device 322detects light passing through the filter. The light source 323 here is,for example, a white LED. By providing a red filter that allows redlight to pass through, a green filter that allows green light to passthrough, and a blue filter that allows blue light to pass through asfilters, the photoelectric conversion device 322 can respectively detectred light, green light, and blue light. By changing the wavelength bandof the light source 323 and a pass band of the filter, the photoelectricconversion device 322 can detect light in various wavelength bands.

2.4 Modifications of Ink Tank

The number of ink tanks 310 included in the electronic apparatus 10 isnot limited to a plurality, and may be one. For example, when theelectronic apparatus 10 includes a printer unit 100 dedicated tomonochrome printing, the printer unit 100 includes one ink tank 310 foraccommodating black ink. In this case, the ink amount can be detected byapplying any of the configurations in FIG. 9, FIG. 25, and FIG. 28 tothe one ink tank 310.

The electronic apparatus 10 may include a plurality of ink tanks 310 asillustrated in FIG. 2. In this case, the ink amount detection processingis executed for a plurality of ink tanks 310, for example. Hereinafter,an example in which all of the plurality of ink tanks 310 are subjectedto ink amount detection will be described, but some of the plurality ofink tanks 310 may be excluded from the targets of ink amount detection.

The electronic apparatus 10 includes a first ink tank, a second inktank, a first photoelectric conversion device, and a secondphotoelectric conversion device. The first ink tank is, for example, theink tank 310 a, and the second ink tank is the ink tank 310 b. Thesecond ink tank is provided in the horizontal direction relative to thefirst ink tank. The horizontal direction is specifically the +Xdirection.

The first photoelectric conversion device is provided on the sidesurface of the first ink tank in a direction orthogonal to the +Xdirection, specifically in the −Y direction, and detects light incidentfrom the first ink tank. The second photoelectric conversion device isprovided on the side surface of the second ink tank in the −Y directionand detects light incident from the second ink tank.

When a plurality of ink tanks 310 are provided, it is efficient toarrange the plurality of ink tanks 310 adjacent to each other.Therefore, it is difficult to arrange the photoelectric conversiondevices 322 on the side surface of the first ink tank on the second inktank side and on the side surface of the second ink tank on the firstink tank side. When there are three or more ink tanks 310, excluding theink tanks 310 at both ends, the side surface in the +X direction and theside surface in the −X direction of the given ink tank 310 are incontact with the side surfaces of other ink tanks 310, it is difficultto dispose the photoelectric conversion device 322 on the side surface.That is, it is desirable that the photoelectric conversion device 322 isprovided on the side surface in the +Y direction or the side surface inthe −Y direction. As illustrated above, in FIG. 9 or the like, thephotoelectric conversion device 322 is provided in the −Y direction withrespect to the ink tank 310.

The print head 107 performs printing by using the ink IKa in the firstink tank and the ink IKb in the second ink tank. The processing unit 120detects the amount of ink in the first ink tank based on the output ofthe first photoelectric conversion device and detects the amount of inkin the second ink tank based on the output of the second photoelectricconversion device. In this way, when the electronic apparatus 10includes a plurality of ink tanks 310, the ink amount detectionprocessing for the plurality of ink tanks 310 can be performed.

The electronic apparatus 10 may include a first light source forirradiating the first ink tank with light, and a second light sourcedifferent from the first light source for irradiating the second inktank with light. The first photoelectric conversion device detects lightfrom the first ink tank in a light emitting period of the first lightsource. The second photoelectric conversion device detects light fromthe second ink tank in a light emitting period of the second lightsource. In this way, since the plurality of ink tanks 310 can beirradiated with light by using respective dedicated light sources, theaccuracy of ink amount detection can be improved.

For example, the first light source irradiates a side surface of thefirst ink tank with light in the −Y direction, and the second lightsource irradiates a side surface of the second ink tank with light inthe −Y direction. In other words, the first light source and the secondlight source emit light on the side surfaces of the ink tank 310 in thedirection in which the first photoelectric conversion device and thesecond photoelectric conversion device are provided, respectively. Forexample, the electronic apparatus 10 includes a plurality of sensorunits 320 illustrated in FIGS. 6 to 8, and the sensor units 320 arerespectively fixed to the side surfaces in the −Y direction of theplurality of ink tanks 310. In this way, the amounts of the ink IKincluded in the plurality of ink tanks 310 can be detected based on thereflected light from the ink tanks 310.

Alternatively, the first light source may emit light on the side surfaceof the first ink tank in the +Y direction, and the second light sourcemay emit light on the side surface of the second ink tank in the +Ydirection. In other words, the first light source and the second lightsource emit light on the side surface of the ink tank 310 in thedirection opposite from the side surfaces provided with the firstphotoelectric conversion device and the second photoelectric conversiondevice. For example, the electronic apparatus 10 includes a plurality oflight receiving units 340 illustrated in FIG. 26 and a plurality oflight emitting units 350 illustrated in FIG. 27. In each ink tank 310 ofthe plurality of ink tanks 310, the light receiving unit 340 is fixed tothe side surface in the −Y direction, and the light emitting unit 350 isfixed to the side surface in the +Y direction. In this way, the amountof the ink IK included in the plurality of ink tanks 310 can be detectedbased on the transmitted light transmitted through the ink tanks 310.

The electronic apparatus 10 is not limited to the configuration in whichthe light source is provided for each ink tank 310. For example, theelectronic apparatus 10 includes one light source that irradiates thefirst ink tank and the second ink tank with light. For example, theelectronic apparatus 10 includes a plurality of light receiving units340 illustrated in FIG. 26, and the light receiving units 340 arerespectively fixed to the side surfaces of the plurality of ink tanks310 in the −Y direction. Similarly to the example illustrated in FIG.28, the light source 323 causes the entire ink tank 310 to emit light byirradiating each ink tank 310 with light from an optional position. Inthis case, one light source 323 irradiates the plurality of ink tanks310 with light. In this way, the amounts of ink IK included in theplurality of ink tanks 310 can be detected based on spatial light of theink tanks 310. As described above, in the method using spatial light, itis sufficient that the entire ink tank 310 emits light, and it is notnecessary to set the light irradiation direction strictly. Therefore,one light source can be shared by the plurality of ink tanks 310.However, it is not hindered to provide a plurality of light sources inthe method using spatial light. For example, the electronic apparatus 10may include a first light source for supplying spatial light to thefirst ink tank and a second light source for supplying spatial light tothe second ink tank.

The first ink tank includes a first filling port and a first dischargingport, and the second ink tank includes a second filling port and asecond discharging port. The first discharging port is provided in the−Y direction with respect to the first filling port, and the seconddischarging port is provided in the −Y direction with respect to thesecond filling port. Thus, it is possible to detect the ink amount at aposition close to the discharging port 312 for each ink tank 310 byusing the photoelectric conversion device 322.

The electronic apparatus 10 may include the ink viewing window portion103 in the first ink tank as described above with reference to FIG. 15.The window portion 103 is closer to the first filling port than to thefirst discharging port. This makes it possible for the user to visuallyrecognize the ink amount for at least one of the plurality of ink tanks310. As illustrated in FIG. 15, a plurality of the window portions 103corresponding to all of the plurality of ink tanks 310 may be provided.A large window portion including an area corresponding to the sidesurfaces of the plurality of ink tanks 310 may be provided. The windowportion 103 may be provided in an area corresponding to some of the inktanks 310 among the plurality of ink tanks 310.

Heretofore, a method of using a plurality of sensor units 320illustrated in FIG. 8 or a method of using a plurality of lightreceiving units 340 illustrated in FIG. 26 has been described. However,the arrangement of the photoelectric conversion device 322 is notlimited to this in a case of detecting the amounts of ink in theplurality of ink tanks 310. For example, on one substrate, both thephotoelectric conversion device 322 for detecting light from the firstink tank and the photoelectric conversion device 322 for detecting lightfrom the second ink tank may be provided.

FIG. 29 is an exploded diagram illustrating the configuration of thesensor unit 360 that detects the ink amounts of the plurality of inktanks 310, and FIG. 30 is a sectional diagram of the sensor unit 360.The sensor unit 360 includes a substrate 361, a photoelectric conversiondevice 322 a, a photoelectric conversion device 322 b, a light source323 a, a light source 323 b, a light guide 324 a, light guide 324 b, alens array 325 a, a lens array 325 b, and a case 365. The photoelectricconversion device 322 a and the photoelectric conversion device 322 bare the same as the photoelectric conversion device 322, respectively.The light source 323 a and the light source 323 b are the same as thelight source 323, respectively. The light guide 324 a and the lightguide 324 b are the same as the light guide 324, respectively. The lensarray 325 a and the lens array 325 b are the same as the lens array 325,respectively.

As illustrated in FIGS. 29 and 30, the case 365 is provided with fouropenings 366 to 369. The photoelectric conversion device 322 a and thelens array 325 a are provided at a position corresponding to the opening366. The light guide 324 a and the light source 323 a are provided at aposition corresponding to the opening 367. The photoelectric conversiondevice 322 b and the lens array 325 b are provided at a positioncorresponding to the opening 368. The light guide 324 b and the lightsource 323 b are provided at a position corresponding to the opening369. Light shielding walls are respectively provided between thephotoelectric conversion device 322 a and the light source 323 a,between the light source 323 a and the photoelectric conversion device322 b, and between the photoelectric conversion device 322 b and thelight source 323 b. In the examples of FIGS. 29 and 30, the lightshielding wall is a part of the case 365.

Light is emitted from the light source 323 a to the first ink tank viathe light guide 324 a, and reflected light of the light is detected bythe photoelectric conversion device 322 a via the lens array 325 a.Light is emitted from the light source 323 b to the second ink tank viathe light guide 324 b, and reflected light of the light is detected bythe photoelectric conversion device 322 b via the lens array 325 b. Thesize of the ink tank 310 and the positional relationship between theplurality of ink tanks 310 are known in the design of the electronicapparatus 10. Thus, proper positional relationship between the lightsource 323 a, the light source 323 b, the photoelectric conversiondevice 322 a, and the photoelectric conversion device 322 b is alsoknown. By making the substrate 361 common, the production of the unitfor detecting the ink amount and the arrangement in the electronicapparatus 10 can be made efficient.

In FIGS. 29 and 30, the sensor unit 360 for detecting the amounts of inkin two ink tanks 310 is exemplified. However, a sensor unit fordetecting the amounts of ink in three or more ink tanks 310 may berealized by using one substrate. In FIGS. 29 and 30, only one case 365is provided, but only the substrate 361 may be shared and one case maybe provided for each ink tank 310 as in FIG. 8.

In the light receiving unit 340 illustrated in FIG. 26 and the lightemitting unit 350 illustrated in FIG. 27, the substrate can be shared.For example, a light receiving unit in which a plurality ofphotoelectric conversion devices 322 for detecting the amounts of ink ina plurality of ink tanks 310 are provided on one substrate may be used.Alternatively, a light emitting unit in which a plurality of lightsources 323 for irradiating the plurality of ink tanks 310 with lightare provided on one substrate may be used.

3. Ink Amount Detection Processing Based on Output of PhotoelectricConversion Device

Next, processing of estimating the amount of ink IK accommodated in theink tank 310 based on the output of the photoelectric conversion device322 will be described. In the following description, any of the variousembodiments described above may be used for the arrangement of thephotoelectric conversion device 322 and the like.

3.1 Basic Ink Amount Detection Processing

FIG. 31 is a waveform representing output data of the photoelectricconversion device 322. As described above with reference to FIG. 13, theoutput signal OS of the photoelectric conversion device 322 is an analogsignal, and output data as digital data is acquired by A/D conversion bythe AFE 130. In order to simplify the description, digital data that isa result of A/D conversion performed on the output signal OS is referredto as “output data of the photoelectric conversion device 322”.

The horizontal axis of FIG. 31 represents a position of thephotoelectric conversion device 322 in the longitudinal direction, andthe vertical axis represents a value of output data corresponding to thephotoelectric conversion element provided at the position. The numericalvalues of the horizontal axis of FIG. 31 represent the distances fromthe reference position in unit of millimeters. FIG. 31 illustratesexamples in which the red LED 323R, the green LED 323G, and the blue LED323B are provided as the light source 323. The processing unit 120acquires three pieces of output data of RGB as output data of thephotoelectric conversion device 322.

When the longitudinal direction of the photoelectric conversion device322 is the vertical direction, the left end of the horizontal axis is aposition corresponding to the photoelectric conversion element providedat the end of the photoelectric conversion device 322 in the +Zdirection, and the right end of the horizontal axis is a positioncorresponding to the photoelectric conversion element provided at theend of the photoelectric conversion device 322 in the −Z direction. Ifthe positional relationship between the photoelectric conversion device322 and the ink tank 310 is known, the horizontal axis can be replacedwith the distances from the reference position of the ink tank 310. Thereference position of the ink tank 310 is, for example, a positionequivalent to the bottom surface of the ink tank 310.

The output data is, for example, 8-bit data, and has a value in therange of 0 to 255. However, the values of the vertical axis can bereplaced with data after the normalization processing or the likedescribed later is performed. The FIG. 31 does not need to includeoutput data corresponding to all photoelectric conversion elementsincluded in the photoelectric conversion device 322, and may be a resultof extracting data corresponding to some of the photoelectric conversionelements, for example, according to the pitch of the optical separator.

As described above, regardless of the configuration of reflected light,transmitted light, or spatial light, the photoelectric conversionelement corresponding to the area where the ink IK does not exist hasrelatively large amount of light received, and the photoelectricconversion element corresponding to the area where the ink IK exists hasrelatively small amount of light received. In the example illustrated inFIG. 31, the value of output data is large in the range indicated by D1,and the value of output data is small in the range indicated by D3. Thevalue of the output data is greatly changed with respect to the changeof the position in the range indicated by D2 between D1 and D3. That is,the range of D1 is an ink non-detection area having a high probabilitythat the ink IK does not exist. The range of D3 is an ink detection areahaving a high probability that the ink IK exists. The range of D2 is anink boundary area representing a boundary between an area where the inkIK exists and an area where the ink IK does not exist.

The processing unit 120 performs the ink amount detection processingbased on the output data of the photoelectric conversion device 322.Specifically, the processing unit 120 detects the position of theinterface of the ink IK based on the output data of the photoelectricconversion device 322. As illustrated in FIG. 31, the interface of theink IK is considered to exist at any position of the boundary area D2.Therefore, the processing unit 120 detects the interface of the ink IKbased on a given threshold Th smaller than the value of the output datain the ink non-detection area and greater than the value of the outputdata in the ink detection area.

For example, the processing unit 120 specifies the maximum value of theoutput data of the photoelectric conversion device 322 as the value ofthe output data in the ink non-detection area. The processing unit 120determines a value smaller than the specified value by a predeterminedamount as the threshold Th. Alternatively, the processing unit 120specifies the minimum value of the output data of the photoelectricconversion device 322 as the value of the output data in the inkdetection area. The processing unit 120 determines a value greater thanthe specified value by a predetermined amount as the threshold Th.Alternatively, the processing unit 120 may determine the threshold Thbased on the average of the maximum value and the minimum value of theoutput data of the photoelectric conversion device 322.

However, when the type of the ink IK and the type of the light source323 are determined, the value of the output data corresponding to theink interface can be determined in advance. Therefore, the processingunit 120 may perform processing of reading out the predeterminedthreshold Th in advance from the storage unit 140 without obtaining thethreshold Th each time.

When the threshold Th is acquired, the processing unit 120 detects aposition where the output value becomes Th as an interface position ofthe ink IK. In this way, the amount of ink included in the ink tank 310can be detected by using the photoelectric conversion device 322 whichis a linear image sensor. Information obtained directly by using Th is arelative position of the ink interface with respect to the photoelectricconversion device 322. Therefore, the processing unit 120 may performcalculation for obtaining the remaining amount of the ink IK based onthe position of the interface.

When all the output data is larger than Th, the processing unit 120determines that ink does not exist in the target range of ink amountdetection, that is, the interface is located at a position lower thanthe end point of the photoelectric conversion device 322 in the −Zdirection. When all the output data is smaller than Th, the processingunit 120 determines that the target range of ink amount detection isfilled with ink, that is, the interface is at a position higher than theend point of the photoelectric conversion device 322 in the +Zdirection. If it is not possible that the interface is located at ahigher position than the end point of the photoelectric conversiondevice 322 in the +Z direction, it may be determined that an abnormalityhas occurred.

The ink amount detection processing is not limited to processing usingthe threshold Th in FIG. 31. For example, the processing unit 120performs processing for obtaining an inclination of the graphillustrated in FIG. 31. The inclination is specifically adifferentiation value and more specifically, a differential valuebetween adjacent output data. When some of the output data are extractedin accordance with the pitch of the optical separator, the adjacentoutput data represent the adjacent data in the extracted data string.The processing unit 120 detects a point where the inclination is largerthan a predetermined threshold, more specifically, a position where theinclination becomes maximum, as the position of the interface. If themaximum value of the obtained inclination is a given inclinationthreshold or less, the processing unit 120 determines that the interfaceis at a position lower than the end point of the photoelectricconversion device 322 in the −Z direction or a position higher than theend point in the +Z direction. Which side the interface is on can beidentified from the value of the output data.

When a plurality of output data are acquired as illustrated in FIG. 31,the ink amount detection processing may be performed based on any one ofthe output data. Alternatively, the processing unit 120 may specify thepositions of respective interfaces using respective output data, anddetermine the final position of the interface based on the specifiedpositions. For example, the processing unit 120 determines, as theinterface position, an average value or the like of an interfaceposition obtained based on output data of R, an interface positionobtained based on output data of G, and an interface position obtainedbased on output data of B. Alternatively, the processing unit 120 mayobtain composite data obtained by combining three pieces of output dataof RGB and obtain the position of the interface based on the compositedata. The composite data is average data obtained by averaging outputdata of RGB at each point, for example.

FIG. 32 is a flowchart for explaining processing including the inkamount detection processing. When the processing is started, theprocessing unit 120 performs control for causing the light source 323 toemit light (S101). Then, in the period during which the light source 323emits light, reading processing using the photoelectric conversiondevice 322 is performed (S102). When the light source 323 includes aplurality of LEDs, the processing unit 120 sequentially performsprocessing of S101 and S102 for each of the red LED 323R, the green LED323G, and the blue LED 323B. Through the above processing, three piecesof output data of RGB illustrated in FIG. 31 are acquired.

Next, the processing unit 120 performs detection processing of the inkamount based on the acquired output data (S103). As described above, thespecific processing of S103 can be variously modified such as comparisonprocessing with the threshold Th and detection processing of the maximumvalue of the inclination.

The processing unit 120 determines the amount of the ink IK in the inktank 310 based on the detected position of the interface (S104). Forexample, the processing unit 120 sets ink amounts in three stages of“large remaining amount”, “small remaining amount”, and “ink end” inadvance, and determines whether the current ink amount corresponds towhich one of them. The large remaining amount represents a state inwhich a sufficient amount of the ink IK is left and no user action isrequired for continuing printing. The small remaining amount representsa state in which the continuation of printing itself is possible but theamount of ink is reduced and replenishment by the user is desirable. Theink end represents a situation where the ink amount is markedly reducedand the printing operation should be stopped.

When it is determined that the remaining amount is large in processingof S104 (S105), the processing unit 120 ends the processing withoutperforming notification or the like. When it is determined that theremaining amount is small in the processing of S104 (S106), theprocessing unit 120 performs notification processing for urging the userto replenish the ink IK (S107). The notification processing is performedby displaying a text or an image on a display unit 150, for example.However, the notification processing is not limited to displaying, andmay be notification by emitting light from a light emitting unit fornotification, notification by sound using a speaker, or notification bycombining these. When the ink end is determined in the processing ofS104 (S108), the processing unit 120 performs notification processing ofurging the user to replenish the ink IK (S109). The notificationprocessing of S109 may be the same as the notification processing ofS107. However, as described above, it is difficult to continue theprinting operation in the ink end, which is a serious state as comparedwith the small remaining amount. Thus, the processing unit 120 mayperform notification processing in S109 different from that of S107.Specifically, the processing unit 120 may execute, in S109, processingof changing the text to be displayed to a content that strongly promptsthe user to replenish ink IK, increasing the light emission frequency,increasing the sound, or the like compared to the processing of S107.The processing unit 120 may perform processing (not illustrated) such asprinting operation stop control after the processing of S109.

The execution trigger for the ink amount detection processingillustrated in FIG. 32 can be set in various ways. For example, theexecution start of a given print job may be used as the executiontrigger or a lapse of a predetermined time may be used as the executiontrigger.

The processing unit 120 may store the ink amount detected by in the inkamount detection processing to the storage unit 140. The processing unit120 performs processing based on the time series change of the detectedink amount. For example, the processing unit 120 obtains an ink increaseamount or an ink decrease amount based on a difference between the inkamount detected at a given timing and the ink amount detected at atiming before the given timing.

Since the ink IK is used for printing, head cleaning, or the like, thereduction of the ink amount is natural in consideration of the operationof the electronic apparatus 10. However, the amount of ink IK consumedper unit time in printing and the amount of ink IK consumed per headcleaning are determined to some extent, and if the amount of consumptionis extremely large, there may be some abnormality such as ink leakage.

For example, the processing unit 120 obtains a standard ink consumptionassumed in printing or the like in advance. The standard ink consumptionmay be obtained based on the estimated ink consumption per unit time orbased on the estimated ink consumption per job. The processing unit 120determines that there is an abnormality when the ink reduction amountobtained based on the time-series ink amount detection processing isequal to or larger than the standard ink consumption by a predeterminedamount or more. Alternatively, the processing unit 120 may performconsumption calculation processing of calculating the amount of inkconsumption by counting the number of times of ejection of the ink IK asdescribed above. In this case, the processing unit 120 determines thatthere is an abnormality when the ink decrease amount obtained based onthe time series ink amount detection processing is larger than the inkconsumption calculated by the consumption calculation processing by apredetermined amount or more.

The processing unit 120 sets an abnormality flag to be ON when theabnormality is determined. In this way, when the ink amount isexcessively reduced, some kind of error processing can be executed.Various processing can be considered when the abnormality flag is set toON. For example, the processing unit 120 may re-execute the ink amountdetection processing illustrated in FIG. 32 with the abnormality flag asa trigger. Alternatively, the processing unit 120 may performnotification processing for urging the user to check the ink tank 310based on the abnormality flag.

The ink amount increases by replenishing the ink IK by the user.However, it is conceivable that the ink amount increases even when theink IK is not replenished, such as temporary interface change due toshaking of the electronic apparatus 10, backflow of ink IK from the tube105, detection error of the photoelectric conversion device 322, or thelike. Therefore, when the ink increase amount is a given threshold orless, the processing unit 120 determines that the ink IK is notreplenished and the increase width is within an allowable error range.In this case, since it is determined that the change in the ink amountis in a normal state, no additional processing is performed.

On the other hand, when the ink increase amount is larger than the giventhreshold, the processing unit 120 determines that the ink isreplenished and sets an ink replenishment flag to ON. The inkreplenishment flag is used as a trigger for executing inkcharacteristics determination processing which will be described later,for example. The ink replenishment flag may be used as a trigger forprocessing of resetting an initial value in the consumption calculationprocessing.

However, when the ink increase amount is larger than the giventhreshold, there may be a possibility of an unacceptably large error dueto some abnormality. Thus, the processing unit 120 performs notificationprocessing for requesting the user to input whether the ink has beenreplenished, and may determine whether to set the abnormality flag orthe ink replenishment flag based on the user input result.

3.2 Ink Droplet

FIG. 33 is a schematic diagram when an ink droplet adheres to the innerwall of the ink tank 310 in the −Y direction, and a schematic diagram ofoutput data of the photoelectric conversion device 322 when an inkdroplet adheres. The ink droplet represents a particle of ink which is aliquid. In FIG. 33, the graph is rotated and described so that thevertical axis represents the position and the horizontal axis representsthe output data of the photoelectric conversion device 322 inconsideration of the positional relationship between the photoelectricconversion device 322 and the ink tank 310.

As described above, the photoelectric conversion device 322 is providedin the −Y direction with respect to the ink tank 310 and detects lightfrom the side surface of the ink tank 310 in the −Y direction. When theink droplet adheres to the inner wall in the −Y direction, sinceabsorption and scattering of light are generated by the ink droplet, theportion corresponding to the ink droplet becomes relatively dark. As aresult, as illustrated in FIG. 33, in the output data of thephotoelectric conversion device 322, the value decreases not only in theposition E1 equivalent to the interface but also in the range from aposition E2 to a position E3 equivalent to the ink droplet.

The processing unit 120 detects a point at which the output data is agiven threshold Th as a position corresponding to the ink interface asdescribed above, for example. As illustrated in FIG. 33, when an inkdroplet adheres, there are a plurality of points at which the outputdata becomes the given threshold Th.

Therefore, the processing unit 120 detects the amount of ink in the inktank based on the lowermost position among the positions where theamount of light detected by the photoelectric conversion device 322satisfies a given condition. A position where the detected light amountsatisfies the given condition is referred to as a candidate position ofthe ink interface. As described above, in the electronic apparatus 10that is a printer includes the print head 107 that performs printing byusing the ink IK in the ink tank 310, the light source 323 thatirradiates the ink tank 310 with light, the photoelectric conversiondevice 322 that detects light incident from the ink tank 310 in a periodduring which the light source 323 emits light, and the processing unit120 that detects the amount of ink in the ink tank 310 based on theoutput of the photoelectric conversion device 322.

Since the ink IK in the present embodiment is a liquid, in the normalusage mode of the electronic apparatus 10, the ink moves in the −Zdirection which is a vertically downward direction, in accordance withgravity and accumulates from the bottom surface of the ink tank 310.Therefore, even if there is a dark area where output data decreases,when there is a brighter air layer vertically downward, it is assumedthat the dark area is not the interface of the ink IK but the inkdroplet. Thus, it is possible to appropriately detect the ink amount byestimating the position of the lowermost position among the candidatepositions of the ink interface as the ink interface. In the case of theexample illustrated in FIG. 33, the processing unit 120 determines thatE3 is the ink droplet among E1 and E3 of which output value is Th orless, and determines that E1 is the ink interface.

The processing unit 120 determines that the given condition is satisfiedwhen it is determined that the amount of change of the light amount isthe first threshold or more. The amount of change of the light amountis, for example, the amount of change with respect to a given referencelight amount. The reference light amount may be a light amountcorresponding to the ink non-detection area as described above or alight amount corresponding to the ink detection area. The amount ofchange of the light amount may be the inclination of the graph. Asdescribed above, the method for estimating the candidate position of theink interface can be variously modified.

When a plurality of candidate positions of the interface are detectedbased on the output of the photoelectric conversion device 322 at thegiven timing, the processing unit 120 may detect the lowermost candidateposition directly as the position of the interface. However, when an inkdroplet adheres to the inner wall of the ink tank 310, it is consideredthat an event having a low occurrence frequency in the normal usagestate of the electronic apparatus 10 has occurred, for example,electronic apparatus 10 is shaken. In this case, since there is apossibility that the state of the ink IK in the ink tank 310 may not bestable, the processing unit 120 may perform the ink amount detectionprocessing again and determines the position of the interface of the inkIK based on the result of the re-detection.

Specifically, when a plurality of candidate positions satisfying thegiven condition are detected in the ink amount detection processing atthe first timing, the processing unit 120 performs the ink amountdetection processing again at the second timing after the lapse of agiven period. The given period here is a short time of several secondsto several tens of seconds. For example, when the ink amount detectionprocessing is performed for each execution of the print job, since theinterval of the ink amount detection processing is longer than theexecution time of the job, the given period here is shorter than that.Thus, when the adhesion of the ink droplet is suspected, the ink amountdetection processing can be quickly executed again.

The processing unit 120 determines the lowermost position among thecandidate positions detected at the first timing as a temporaryinterface, and determines whether the temporary interface is determinedas the ink interface based on comparison processing between thedetection result at the second timing and the detection result at thefirst timing. For example, when it is determined that the differencebetween the detection result at the second timing and the detectionresult at the first timing is small, the processing unit 120 determinesthat the state of the ink IK is stable and the temporary interface isdetermined as the ink interface. The small difference indicates, forexample, that the change in the position of the point at which theoutput data is a given threshold in the Z-axis is small. In determiningwhether the temporary interface is reliable, it is important whether thestate of ink IK is stable in the vicinity of the temporary interface.Therefore, it is not necessary to compare all of the detection resultsat the second timing and the detection results at the first timing, andfor example, information on a position close to the temporary interfacemay be compared.

FIG. 34 is a flowchart for explaining the ink amount detectionprocessing including processing related to the ink droplet. Processingof S201 and S202 in FIG. 34 is the same as processing of S101 and S102in FIG. 32. Next, the processing unit 120 performs the ink amountdetection processing. Specifically, a point at which the output databecomes the threshold Th is detected (S203). When the ink drop exists,there are a first feature point that changes from a value larger thanthe threshold Th to a threshold Th or less and a second feature pointthat changes from a value equal to or less than the threshold Th to avalue greater than the threshold Th, in the −Z direction at the pointwhere the output data becomes the threshold Th. In the exampleillustrated in FIG. 33, E1 and E3 are the first feature points, and E2is the second feature point. Since the number of ink droplets is notlimited to one, three or more first feature points and two or moresecond feature points may be detected. The processing unit 120determines the first feature point as a candidate position of theinterface. In the example illustrated in FIG. 33, the candidatepositions of the interface are E1 and E3, and E1 is the lowermostcandidate position between them. The processing unit 120 also stores thesecond feature point in the storage unit 140.

Next, the processing unit 120 determines whether a plurality ofcandidate positions of the interface are detected (S204). When there isone candidate position (Yes in S204), the one candidate position isdetermined as the position of the interface (S205). When a plurality ofcandidate positions are detected (No in S204), detection processing isexecuted again after defining the lowermost position of the firstfeature points as the temporary interface. Specifically, the processingunit 120 performs control for causing the light source 323 to emit light(S206), and performs light reception control of the photoelectricconversion device 322 during a light emission period of the light source323 (S207). The processing unit 120 detects the first feature point andthe second feature point where the output data is the threshold Th(S208).

The processing unit 120 performs processing of comparing the detectionresult in S203 with the detection result in S208 (S209). For example,comparison of the lowermost points among the first feature points andcomparison of the lowermost points among the second feature points areperformed. The processing unit 120 determines whether the change betweenthe two detection results is small based on the comparison processing(S210).

When both the changes of the two points are a predetermined level orless (Yes in S210), the degree of change in the vicinity of at least thetemporary interface is small, and it is determined that the detectionresult is reliable. Therefore, the processing unit 120 detects theposition of the interface based on the temporary interface detected inS203 (S211). Note that the processing unit 120 may directly use theposition of the temporary interface as the position of the interface,may use the position of the lowermost first feature point detected inS208 as the position of the interface, or may determine the position ofthe interface based on an average or the like of the two positions. InFIG. 34, the processing is finished after the determination of theposition of the interface, but the processing may be shifted to theprocessing of S104 in FIG. 32.

When it is determined that the change between the two detection resultsis large (No in S210), the processing returns to S204, for example, andperforms processing of determining the interface again. However, variousmodifications can be executed for the processing when No is determinedin S210, for example, when the processing is finished withoutdetermining the position of the interface.

3.3 Shading Correction

The photoelectric conversion device 322 of the present embodimentincludes a plurality of photoelectric conversion elements. Since thecharacteristics of the photoelectric conversion elements are varied, theoutput may vary depending on the photoelectric conversion elements evenwhen light of the same intensity is incident. There is a possibilitythat the detection accuracy of the ink amount may be lowered due to thisvariation. For example, when the output of a given photoelectricconversion element is lowered compared with the output of a peripheralphotoelectric conversion element, the processing unit 120 may not beable to determine whether the output is lowered due to the presence ofink IK or the output is lowered due to the variation in thephotoelectric conversion elements. Therefore, preferably, the processingunit 120 performs the correction processing on the output data of thephotoelectric conversion device 322, and performs the ink amountdetection processing based on the data after the correction processing.Similarly, regarding the ink characteristics determination processingwhich will be described later, there is a possibility that theprocessing accuracy may be lowered due to the characteristics variationin the photoelectric conversion elements. By performing the correctionprocessing, the accuracy of the ink characteristics determinationprocessing can be improved.

Shading correction is widely used in the linear image sensor used in ascanner. For example, the scanner incorporates a color reference plateused for shading correction. Specifically, the color reference plate isa white reference plate as a white reference. A white reference value isacquired by performing reading processing of a white reference plate ina state where the light source is turned on. A black reference value isacquired by performing reading processing in a state where the lightsource is turned off. The scanner performs shading correction processingbased on the white reference value and the black reference value withrespect to digital data being the reading result of the photoelectricconversion element, and outputs an image based on the corrected data.

In the present embodiment, by performing correction processing similarto that of the scanner, variation in photoelectric conversion elementscan be suppressed. However, as illustrated in FIG. 31, the processingunit 120 of the present embodiment performs the ink amount detectionprocessing based on the difference of brightness between the area wherethe ink IK is not filled and the area where the ink IK is filled. Thatis, it is not assumed that the photoelectric conversion device 322 usedfor the ink amount detection processing detects light having a largeramount of light than light from the area where the ink IK is not filled.The side surface of the ink tank 310 is formed of a light transmissivemember such as a resin, and the reflectance is not as higher as that ofthe white reference plate. Therefore, in the case where the output datawhen the white reference plate is read is used as the white referencevalue, the area near the maximum value is not used in the actual inkamount detection processing. Since the data is processed using a narrownumerical range, the resolution is lowered, and the accuracy of the inkamount detection processing may be lowered. In the first place, theprinter unit 100 and the ink tank unit 300 often do not include thewhite reference plate.

The method of the present embodiment is applicable to a productionmethod of a printer which detects the ink amount in the ink tank 310using the light source 323 and the photoelectric conversion device 322.The production method includes a first step of irradiating the ink tank310 with light from the light source 323 in a state where the ink IK isnot filled in the ink tank 310, and detecting light from the ink tank310 using the photoelectric conversion device 322. Also, the productionmethod includes a second step of storing a first correction parameter ofthe output of the photoelectric conversion device 322 in a non-volatilestorage unit of the printer, based on the output of the photoelectricconversion device 322 in the first step. The non-volatile storage unitis included in, for example, a storage unit 140. The storage unit 140may include a volatile storage unit in addition to the non-volatilestorage unit.

In the first step, “unfilled” means that ink is not filled in an areafacing the photoelectric conversion device 322 in the ink tank 310. Thatis, the first step is not prevented from being executed in a state wherethe ink IK is filled in the area in the −Z direction with respect to theposition where the photoelectric conversion device 322 is provided.Alternatively, the first step may be executed when the ink IK is oncefilled and the ink is discharged and not filled. The state at this timeis also “unfilled” because the ink will be filled later. The processingunit 120 performs light emission control of the light source 323 andlight reception control of the photoelectric conversion device 322. Whenthe light source 323 includes the red LED 323R, the green LED 323G, andthe blue LED 323B, the first correction parameter may be obtained bycausing any one LED to emit light, but it is not hindered to obtain thefirst correction parameter individually for each emission color. Thefirst correction parameter stored in the storage unit 140 is a set ofvalues corresponding to the number of photoelectric conversion elements.

The first correction parameter is a white reference parameter. In thisway, for each element of the plurality of photoelectric conversionelements, correction is performed so that the value of the output datain the ink non-detection area becomes a value near the maximum value.Thus, since variation in the photoelectric conversion elements issuppressed and the range of output data is effectively utilized, theaccuracy of ink amount detection processing can be improved.

Further, the photoelectric conversion device 322 used for the ink amountdetection processing is not assumed to receive light having a smalleramount of light than light from the area filled with the ink IK. Whencorrection processing is performed with output data in a state where thelight source 323 is turned off as a reference value, the area near theminimum value is not used in actual ink amount detection processing.Thus, the accuracy of ink amount detection processing may be reduced.

Therefore, the production method of the printer according to the presentembodiment may include a third step of irradiating the ink tank 310 withlight from the light source 323 and detecting light from the ink tank310 using the photoelectric conversion device 322 in a state where theink tank 310 is filled with the ink IK. The production method includes afourth step of storing a second correction parameter of the output ofthe photoelectric conversion device in a non-volatile storage unit ofthe printer based on the output of the photoelectric conversion device322 in the third step.

In the third step, “filling” means that at least an area of the ink tank310 facing the photoelectric conversion device 322 is filled with ink,and the specific amount of ink IK can be variously modified.

The second correction parameter is a parameter of a black reference. Inthis way, for each element of the plurality of photoelectric conversionelements, correction is performed so that the value of the output datain the ink detection area becomes a value near the minimum value. Byusing both the white reference parameter and the black referenceparameter, variation in the photoelectric conversion elements is furthersuppressed and the range of output data is effectively utilized, therebyimproving the accuracy of ink amount detection processing.

When the photoelectric conversion device 322 is provided in each of theplurality of ink tanks 310, ink IK corresponding to the target ink tank310 may be filled in the third step for each photoelectric conversiondevice 322. For example, in the third step for the photoelectricconversion device 322 for detecting the amount of yellow ink IK, in astate where the yellow ink IK is filled, the ink tank 310 is irradiatedwith light from the light source 323, and light from the ink tank 310 isdetected using the photoelectric conversion device 322. In the thirdstep for the photoelectric conversion device 322 for detecting theamount of the magenta ink, the magenta ink IK is filled. In this way,the data range can be appropriately expanded. However, filling of thesame ink IK for inspection is not hindered for all the ink tanks 310 inconsideration of a reduction in manufacturing burden. In this case also,the deterioration of accuracy caused by variation in the photoelectricconversion elements can be suppressed.

The correction processing using the first correction parameter and thesecond correction parameter is performed by equation (1). In equation(1), W represents the first correction parameter which is the parameterof the white reference. B represents the second correction parameterwhich is the parameter of the black reference. E is output data beforethe correction processing, and E′ is output data after the correctionprocessing.

$\begin{matrix}{E^{\prime} = \frac{E - B}{W - B}} & (1)\end{matrix}$

The processing unit 120 acquires output data after A/D conversion fromthe AFE 130, and performs correction processing using the above equation(1) on each output data. Then, the processing unit 120 performs the inkamount detection processing and the ink characteristics determinationprocessing described later based on the output data after the correctionprocessing. In the case of using the above equation (1), E′ is data of 0or more and 1 or less. However, the numerical range of E′ may be changedby multiplying the right side of the equation (1) by a givencoefficient. For example, when the output data is set to 8 bits, theprocessing unit 120 multiplies the right side by 255 and then convertsit to an integer, and sets the result as corrected output data E′.

FIG. 35 is a schematic diagram for explaining a change in output datadue to the correction processing. F1 in FIG. 35 represents data beforethe correction processing, and F2 represents data after the correctionprocessing. In both F1 and F2, the horizontal axis represents a positionin the photoelectric conversion device 322, and the vertical axisrepresents output data of the photoelectric conversion elementcorresponding to the position.

F11 is an example of output data detected in the first step, that is,the first correction parameter. Despite the incidence of light from anarea that is not filled with ink IK on all the photoelectric conversionelements, values vary due to variation in the photoelectric conversionelements. F12 is an example of output data detected in the third step,that is, the second correction parameter. Despite the incidence of lightfrom an area that is filled with ink IK on all the photoelectricconversion elements, values vary due to variation in the photoelectricconversion elements. Further, since the output data in the ink amountdetection processing has a value between F11 and F12, for example, arange indicated by F13, the output data is narrower than F14, which is anumerical value range that the output data can take.

F21 is a correction result for the output data detected in the firststep. As indicated by F21, since correction processing is performed sothat output data corresponding to the area not filled with ink IK hasthe maximum value max, variation in data is suppressed. F22 is acorrection result for the output data detected in the third step. Asindicated by F22, since correction processing is performed so thatoutput data corresponding to the area filled with the ink IK has theminimum value min, the variation in data is suppressed. Further, sincethe output data in the ink amount detection processing has a valuebetween F21 and F22, a numerical range that the output data can take canbe effectively utilized.

As illustrated in the above equation (1) and FIG. 35, the firstcorrection parameter is a normalization parameter of the output of thephotoelectric conversion device 322. Similarly, the second correctionparameter is a normalization parameter of the output of thephotoelectric conversion device 322. That is, correction processing inthe present embodiment is normalization processing based on the firstcorrection parameter. By using the output data after the normalizationprocessing, the accuracy of ink amount detection processing or the likecan be improved.

However, the production method of the printer according to the presentembodiment is not limited to one including all the first to fourthsteps. In the manufacturing step of the printer, it is considered normalthat the ink tank 310 is not filled with ink IK. Thus, the first step iseasily implemented. On the other hand, in the third step, it isnecessary to fill the ink tank 310 with ink IK to the extent that theink IK exists at least at a portion, facing the photoelectric conversiondevice 322, of the ink tank 310. Therefore, the case where the thirdstep can be executed is limited, or the filling of ink IK is requiredonly for executing the third step.

Therefore, the production method of the printer according to the presentembodiment may include a fifth step of detecting light from the ink tank310 using the photoelectric conversion device 322 in a state where thelight source 323 is not caused to radiate light, and a sixth step ofstoring a third correction parameter of the output of the photoelectricconversion device 322 in the non-volatile storage unit of the printerbased on the output of the photoelectric conversion device 322 in thefifth step. The third correction parameter is a parameter of the blackreference.

The fifth step and the sixth step are performed in place of the thirdstep and the fourth step. In this way, the parameter of the blackreference can be easily acquired as compared with the case where thethird step is performed. The processing unit 120 executes correctionprocessing on the output data of the photoelectric conversion device 322based on the first correction parameter and the third correctionparameter. The third step is advantageous from the viewpoint of therange of the output data, and the fifth step is advantageous from theviewpoint of the easiness of measurement.

3.4 Correction Processing by Mark

As described above with reference to FIG. 31, what is required in theink amount detection processing is information indicating which one ofthe plurality of photoelectric conversion elements included in thephotoelectric conversion device 322 has a position corresponding to theink interface. In order to specify the ink amount, the position of theink interface in the ink tank 310 is required. That is, in order tospecify the ink amount, the positional relationship between the ink tank310 and the photoelectric conversion device 322 has to be known.

For example, the sensor unit 320 is fixed to a predetermined position ofthe ink tank 310 based on the design. Since the error in mounting of thephotoelectric conversion device 322 on the substrate 321 is consideredto be sufficiently small, when the sensor unit 320 is fixed to the inktank 310 as designed, the positional relationship between the ink tank310 and the photoelectric conversion device 322 also becomes asdesigned. However, the positional relationship between the sensor unit320 and the ink tank 310 may not coincide with that of the design due tothe assembly error.

FIG. 36 is a schematic diagram illustrating the assembly error of thesensor unit 320. The sensor unit 320 is designed to be fixed at theposition indicated by G1, but may be fixed at the position indicated byG2 that is shifted in the +Z direction due to the assembly error. Whenthe sensor unit 320 is shifted in the +Z direction, the processing unit120 detects the ink interface at the position of the photoelectricconversion element in the −Z direction rather than the photoelectricconversion element originally corresponding to the ink interface.Therefore, it is determined that the ink amount is smaller than theactual amount. On the contrary, when the sensor unit 320 is shifted inthe −Z direction, the processing unit 120 detects the ink interface atthe position of the photoelectric conversion element in the +Z directionrather than the photoelectric conversion element originallycorresponding to the ink interface. Therefore, it is determined that theink amount is larger than the actual amount. Thus, the assembly error inthe Z-axis becomes a factor for lowering the accuracy of the ink amountdetection processing. Although errors in the horizontal direction,particularly in the X-axis, can be generated, the assembly errors in thehorizontal direction do not lead to erroneous determination of theinterface position. The sensor unit 320 is illustrated in FIG. 36, butthe same applies to the case of using the light receiving unit 340.

The electronic apparatus 10 of the present embodiment includes the inktank 310 with a mark MK attached to its side surface. The photoelectricconversion device 322 is provided outside the side surface to which themark MK is attached out of the side surfaces of the ink tank 310, anddetects light from the ink tank 310 in a period during which the lightsource 323 emits light. The processing unit 120 determines the positionof the interface of the ink IK based on the output of the photoelectricconversion device 322, and detects the amount of ink in the ink tank 310based on the position of the mark MK and the position of the interface.

FIG. 37 is a schematic diagram illustrating the relationship between theposition of the mark MK and the assembly error of the photoelectricconversion device 322. For example, the photoelectric conversion device322 is provided in the −Y direction of the ink tank 310, and the mark MKis attached to the side surface of the ink tank 310 in the −Y direction.Due to the assembly error, the sensor unit 320 may be fixed at theposition indicated by H1, or may be fixed at the position indicated byH2. The position of the interface detected by the photoelectricconversion device 322 changes between H1 and H2. However, since theposition of the mark MK detected by the photoelectric conversion device322 is also changed, the difference between the position of the mark MKand the position of the interface is common between H1 and H2. Since theposition of the mark MK in the ink tank 310 is known in design, theprocessing unit 120 can appropriately determine the position of theinterface in the ink tank 310 even when the assembly error occurs. Forexample, if the distance from the bottom surface of the ink tank 310 tothe mark MK is known, the processing unit 120 can calculate the distancefrom the bottom surface of the ink tank 310 to the interface based onthe difference between the position of the mark MK and the position ofthe interface.

The mark MK is a member that is provided at a given position of the inktank 310 in the Z-axis, and has a smaller light transmittance than themembers constituting the ink tank 310. For example, the mark MK is acoating layer provided on the outer wall of the ink tank 310.Alternatively, when the ink tank 310 is formed by two-color molding, themark MK is made of a member having relatively low light transmittance,and a portion other than the mark MK is made of a member havingrelatively high light transmittance. That is, the mark MK can berealized by the same configuration as the first layer to the third layerwhen the optical separator is provided on the side surface of the inktank 310. In this way, the positional relationship between thephotoelectric conversion device 322 and the mark MK can be estimatedbased on the output of the photoelectric conversion device 322.

FIG. 38 is a schematic diagram for explaining the relationship betweenthe mark MK and the output data of the photoelectric conversion device322. Since the light emitted from the area to which the mark MK isattached to the photoelectric conversion device 322 becomes very weaklight, the output data corresponding to the position of the mark MK ismade smaller than the peripheral output data to the extent to beidentifiable. Thus, the position of the mark MK in the photoelectricconversion device 322 can be specified by making the opticalcharacteristics of the mark MK different from those of the wall surfaceof the ink tank 310.

As described above, the processing unit 120 performs ink amountdetection processing based on the relative position of the mark MK andthe interface on the Z-axis. Therefore, the position of the mark MK onthe Z-axis in the ink tank 310 needs to be a given fixed value. Forexample, the mark MK may be a point provided at a predetermined positionon the side surface of the ink tank 310. The point is, for example, aminute circular shape having a size capable of suppressing lightincident on a given photoelectric conversion element.

However, the positional relationship between the photoelectricconversion device 322 and the ink tank 310 on the X-axis may change dueto the assembly error. When the length of the mark MK on the X-axis isshort, there is a possibility that the positional relationship in whichthe mark MK and the photoelectric conversion device 322 do not face eachother may be caused by the assembly error. Therefore, the mark MK ispreferably a shape including a line in the horizontal direction.

For example, the mark MK is a line segment extending in the horizontaldirection as illustrated in FIG. 38, specifically, is a rectangle withthe Z-axis as the short side direction and the X-axis as thelongitudinal direction. By using such a mark MK, it is possible toappropriately detect the mark MK by the photoelectric conversion device322 even when the assembly error in the horizontal direction occurs.However, the mark MK may include a line in the horizontal direction at aportion of a boundary between the area of the mark MK and an area otherthan the mark MK, and the shape thereof is not limited to a rectangle.For example, the mark MK may be a triangle provided so that any one sidethereof is horizontal. In this case, the processing unit 120 uses theposition of the horizontal side of the mark MK for the ink amountdetection processing. The concrete shape of the mark MK can be variouslymodified.

As illustrated in FIG. 38, the mark MK can be detected as a positionwhere the output data is locally decreased. Therefore, the processingunit 120 may perform processing of determining the position of the markMK based on the output of the photoelectric conversion device 322. Forexample, the processing unit 120 performs both the detection processingof the mark MK and the detection processing of the interface every timewhen performing the ink amount detection processing.

However, it is considered that, once the assembly is performed, thepositional relationship between the ink tank 310 and the photoelectricconversion device 322 is not changed significantly thereafter.Therefore, the electronic apparatus 10 may include a non-volatilestorage circuit for storing information representing the position of themark MK. The processing unit 120 detects the ink amount by readinginformation indicating the position of the mark MK from the non-volatilestorage circuit. In this case, since the information that has alreadybeen obtained can be used for the position of the mark MK, theprocessing unit 120 can detect the ink amount by detecting the interfaceof the ink IK from the output data. For example, the processing unit 120obtains the mark MK in the first ink amount detection processing, andwrites the obtained position of the mark MK in the storage unit 140. Inthe subsequent ink amount detection processing, the processing unit 120continuously utilizes the position of the mark MK that has been written.Thus, the position of the mark can be identified even in a situationwhere the identification of the mark is difficult because the interfaceof the ink exists above the position of the mark.

Alternatively, the position of the mark MK may be written in the storageunit 140 at the manufacturing stage. For example, the production methodof the printer according to the present embodiment includes a seventhstep of storing a fourth correction parameter representing the positionof the mark MK in a non-volatile storage unit of the printer based onthe output of the photoelectric conversion device 322 in the first step.Here, in the first step, an example of acquiring the fourth correctionparameter together with the first correction parameter which is aparameter of white correction is exemplified, but it is not limitedthereto. For example, the production method of the printer may includean eighth step, which is different from the first step, of irradiatingthe ink tank 310 with light from the light source 323 and detectinglight from the ink tank 310 using the photoelectric conversion device322. In this case, the production method includes a seventh step ofstoring the fourth correction parameter representing the position of themark MK in a non-volatile storage unit of the printer based on theoutput of the photoelectric conversion device 322 in the eighth step.

In the ink tank 310, a slit which is an optical separator for separatinglight in the vertical direction may be provided on the side surface. Inthis case, since the optical separator includes an area with low lighttransmittance, the optical characteristics difference between the areaand the mark MK is small. Therefore, in this case, it is preferable thatthe length of the mark MK in the vertical direction is longer than thepitch of the slit.

FIG. 39 is a schematic diagram illustrating the side surface of the inktank 310 provided with both the optical separator and the mark MK. Whenthe optical separator is provided, areas with a large amount of lightreaching the photoelectric conversion device 322 from the ink tank 310and areas with a small amount thereof appear alternately, in the Z-axis.As illustrated in FIG. 38, it is difficult to determine whether thereduction is caused by the optical separator or the mark MK, only bysimply detecting the reduction of the output data. On the other hand,after changing the lengths of the optical separator and the mark MK, theprocessing unit 120 detects a range where the output data decreases. Forexample, in −Z direction, the processing unit 120 detects a point wherethe output data changes from a value larger than a given threshold to avalue equal to or smaller than the threshold, and a point where theoutput data changes from a value equal to or smaller than the thresholdto a value larger than the threshold, thereby obtaining the lengthbetween the two points.

In the example illustrated in FIG. 39, since the reduction range of thedata caused by the mark MK is about three times as long as the reductionrange of the data caused by the optical separator, the mark MK and theoptical separator can be appropriately identified. As described above,the resolution in the ink amount detection processing is determined bythe arrangement pitch of photoelectric conversion elements in thephotoelectric conversion device 322 and the wider optical separationpitch of the optical separator. The pitch of the optical separator ispreferably narrowed as much as possible, considering the resolution.Therefore, when a difference is provided between the lengths of theoptical separator and the mark MK, it is easier to form the mark MK whenthe mark MK is made longer, and it is possible to suppress a decrease inresolution.

Heretofore, an assembly error in the translation direction of thephotoelectric conversion device 322 has been described. However, theassembly errors can occur in the rotational direction. FIG. 40 is aschematic diagram illustrating a relationship between the ink tank 310and the photoelectric conversion device 322 when the photoelectricconversion device 322 rotates around the Y-axis by θ. As illustrated inFIG. 40, the distance between the mark MK and the interface on theZ-axis is H1. However, the processing unit 120 performs the ink amountdetection processing on the assumption that the photoelectric conversiondevices 322 are arranged along the Z-axis. Therefore, the processingunit 120 determines that the distance between the mark MK and theinterface on the Z-axis is H2. By determining that the distance from themark MK to the interface is excessively long, it is determined that theink amount is smaller than the actual amount. Thus, the assembly errorin the rotational direction also becomes a factor of lowering theaccuracy of the ink amount detection processing.

The photoelectric conversion device 322 according to the presentembodiment may include a first linear image sensor provided on thesubstrate 321 and a second linear image sensor provided on the substrate321. The processing unit 120 estimates the inclination of thephotoelectric conversion device 322 with respect to the ink tank 310based on the position of the mark MK determined from the first linearimage sensor and the position of the mark MK determined from the secondlinear image sensor.

FIGS. 41 and 42 are diagrams for explaining the positional relationshipbetween the ink tank 310, the first linear image sensor, and the secondlinear image sensor. FIG. 41 illustrates a positional relationship in astate where no assembly error occurs. For example, the first linearimage sensor and the second linear image sensor are sensor chips havingthe same length and the same element pitch. In the example illustratedin FIG. 41, when no assembly error occurs, the position of the mark MKin the first linear image sensor coincides with the position of the markMK in the second linear image sensor. The position of the interface inthe first linear image sensor coincides with the position of theinterface in the second linear image sensor. The positional relationshipbetween the first linear image sensor and the second linear image sensormay be known, and the length, the element pitch, the position in theZ-direction, or the like are not limited to examples in FIG. 41.

FIG. 42 illustrates the positional relationship when the photoelectricconversion device 322 rotates by θ1 with respect to the ink tank 310.The position of the mark MK in the second linear image sensor is shiftedby I1 as compared with the position of the mark MK in the first linearimage sensor. Since the distance I2 between the two linear image sensorsis known, a rotation angle θ1 due to an assembly error is obtained bythe following equation (2). When θ1 is obtained, the actual distance I4between the mark MK and the interface is obtained by equation (3).

$\begin{matrix}{{\theta 1} = {\tan^{- 1}\left( \frac{I\; 1}{I\; 2} \right)}} & (2) \\{{I\; 4} = {I\; 3 \times \cos\;\theta\; 1}} & (3)\end{matrix}$

Thus, by using two linear image sensors for one ink tank 310, theinclination of the photoelectric conversion device 322 with respect tothe ink tank 310 can be detected. Thus, even when the assembly error inthe rotational direction occurs, the ink amount detection processing canbe performed with high accuracy. The two linear image sensors need to bearranged not side by side in the longitudinal direction. Morepreferably, the second linear image sensor is disposed at a certaininterval in a direction intersecting the longitudinal direction of thefirst linear image sensor. This is because even if the rotation angle θ1is the same, the difference I1 between the detection positions of thetwo linear image sensors increases as the interval I2 increases.However, since the two linear image sensors need to detect the same inktank 310, the interval cannot be excessively widened. Therefore, it isdesirable to set an appropriate value for the interval between the twolinear image sensors based on the shape of the ink tank 310 or the like.

The processing unit 120 may estimate an inclination φ of the ink tank310 with respect to the horizontal plane based on the position of theinterface determined from the first linear image sensor and the positionof the interface determined from the second linear image sensor.

FIG. 43 is a schematic diagram when the ink tank 310 is inclined withrespect to an XY plane which is the horizontal plane. FIG. 43illustrates an example in which the photoelectric conversion device 322is fixed at an appropriate angle with respect to the ink tank 310. Asillustrated in FIG. 43, when the ink tank 310 is inclined with respectto the horizontal plane, the line representing the mark MK rotates inaccordance with the rotation of the ink tank 310, but the ink interfacecoincides with the horizontal plane.

The position of the interface in the second linear image sensor isshifted by J1 as compared with the position of the interface in thefirst linear image sensor. Since the distance J2 between the two linearimage sensors is known, the rotation angle θ2 of the photoelectricconversion device 322 with respect to the horizontal plane is obtainedby the following equation (4). In FIG. 43, an example is considered inwhich the assembly error in the rotational direction of the ink tank 310and the photoelectric conversion device 322 is not generated. Therefore,the inclination φ of the ink tank 310 with respect to the horizontalplane is equal to the rotation angle θ2 of the photoelectric conversiondevice 322 with respect to the horizontal plane.

$\begin{matrix}{{\theta 2} = {\tan^{- 1}\left( \frac{J\; 1}{J2} \right)}} & (4)\end{matrix}$

In the case of the state illustrated in FIG. 43, since the ink tank 310itself is inclined, the ink amount cannot be specified only from theinterface at one given point. In order to specify the ink amount,arithmetic processing using the position of the interface at the givenpoint, the inclination angle φ of the ink tank 310, and the shape of theink tank 310 is required. The processing unit 120 may determine the inkamount by performing such a calculation. Alternatively, when theinclination of the ink tank 310 is detected, the processing unit 120 mayperform processing for notifying the user of the fact and skip thecalculation of the ink amount.

The processing unit 120 may obtain both the inclination θ1 of thephotoelectric conversion device 322 with respect to the ink tank 310 andthe inclination φ of the ink tank 310 with respect to the horizontalplane. That is, the situation that the photoelectric conversion device322 rotates by θ1 with respect to the ink tank 310, and the ink tank 310inclines by φ with respect to the horizontal plane may be taken intoconsideration.

As illustrated in FIGS. 42 and 43, the inclination θ1 of thephotoelectric conversion device 322 with respect to the ink tank 310 isobtained based on the difference in the positions of the marks MK in thetwo linear image sensors. Further, the inclination θ2 of thephotoelectric conversion device 322 with respect to the horizontal planeis obtained based on the difference in the positions of the interfacesin the two linear image sensors. The inclination φ of the ink tank 310with respect to the horizontal plane is obtained based on θ1 and θ2. Forexample, φ is a difference between θ1 and θ2. That is, even when boththe inclination of the photoelectric conversion device 322 with respectto the ink tank 310 and the inclination of the ink tank 310 with respectto the horizontal plane are generated, the processing unit 120 cancalculate each inclination based on two linear image sensors providedfor the same ink tank 310.

4. Determination Processing of Ink Characteristics Based on Output ofPhotoelectric Conversion Device

The electronic apparatus 10 according to the present embodiment is aprinter including the ink tank 310, the print head 107, the light source323, the photoelectric conversion device 322, and the processing unit120. The processing unit 120 determines the ink characteristics in theink tank 310 based on the characteristics of the light amount detectedby the photoelectric conversion device 322.

As described above with reference to FIGS. 2 and 3, the electronicapparatus 10 may include a plurality of ink tanks 310 filled withdifferent kinds of ink IK. In this case, there is a possibility that theuser erroneously fills the other ink tank 310 such as the ink tank 310 bwith the ink IKa to be filled in the ink tank 310 a. Even if theelectronic apparatus 10 is a monochrome printer having one ink tank 310,if the user uses printers of different models together, there is apossibility that the ink IK used for another printer is erroneouslyfilled. Furthermore, even when the user uses only one monochromeprinter, since many different inks are distributed in the marketdepending on the model, the possibility that the user erroneouslypurchases and fills ink for the different model cannot be denied.

For example, when the ink tank 310 to be filled with yellow ink isfilled with magenta ink, the color of the printing result largelydeviates from the desired color. That is, in order to performappropriate printing, it is necessary to appropriately detect the errorof the color of the ink. Therefore, the processing unit 120 determinesthe color characteristics of the ink as the ink characteristics.

FIG. 44 is a diagram comparing output data of the photoelectricconversion device 322 for two inks IK having different colorcharacteristics. K1 in FIG. 44 is an example of output data of thephotoelectric conversion device 322 when measurement is performed forthe ink tank 310 filled with yellow ink. K2 is an example of output dataof the photoelectric conversion device 322 when measurement is performedfor the ink tank 310 filled with magenta ink. The horizontal axes of K1and K2 represent positions in the photoelectric conversion device 322,and the vertical axes represent output data corresponding to thepositions. In FIG. 44, the position of ink interface is made common toK1 and K2. However, as will be described later, the output data in theink boundary area or the ink detection area may be acquired in the inkcharacteristics determination processing, and the position of the inkinterface is optional.

FIG. 44 illustrates the result of performing the correction processingindicated by the above equation (1) with the first correction parameteras the white reference parameter and the third correction parameter asthe black reference parameter. The third correction parameter is aparameter acquired in a state where the ink IK is not filled. Therefore,as illustrated in FIG. 44, data in the ink detection area does notbecome a value close to 0, but becomes a different value depending onthe color characteristics of the target ink IK.

In the example illustrated in FIG. 44, when yellow ink is the target,the signal value in the ink amount detection area is a value around 0.55when any of RGB illumination light is used. On the other hand, when themagenta ink is the target, the signal value in the ink amount detectionarea is a value around 0.40 when any of RGB illumination light is used.

The processing unit 120 determines the ink characteristics based on thelight amount in the ink detection area which is an area where it isdetermined that ink IK exists in the ink tank. In other words, theprocessing unit 120 uses the value of the output data in the inkdetection area as a feature amount for determining the inkcharacteristics. As described above, the magnitude of the light amountis detected as the magnitude of the output data based on thephotoelectric conversion device 322.

The processing unit 120 first specifies an ink detection area. Forexample, the processing unit 120 specifies an area where the inclinationis an inclination threshold or less and the data value is smaller than 1by a predetermined amount or more as the ink detection area. Theprocessing unit 120 obtains the minimum value of data in the inkdetection area as the ink characteristics determination feature amount.In the example illustrated in FIG. 44, the processing unit 120 may useany of RGB data to obtain the minimum value. Alternatively, compositedata obtained by combining two or more pieces of data among RGB may beobtained, and the minimum value in the ink detection area of thecomposite data may be obtained. The composite data is average dataobtained by averaging RGB data at each point, for example.

In the example illustrated in FIG. 44, the processing unit 120determines that the ink IK is yellow ink when the obtained minimum valueis close to 0.55, and that the ink IK is magenta ink when it is close to0.40. Although an example using the minimum value is exemplified here,other statistical values such as the average value and the median valueof the output data in the ink detection area may be used.

As described above, in the ink characteristics determination processing,it is important to determine whether a given ink tank 310 is filled withan erroneous ink IK. Therefore, the processing unit 120 determineswhether the ink IK other than the yellow ink is filled in the yellow inktank 310, and does not need to specify a specific color of the ink IK.For example, when the ink tank 310 for yellow ink is targeted, theprocessing unit 120 compares the output data in the ink detection areawith 0.40 as a reference value of yellow ink, and determines abnormalitywhen the difference is equal to or more than a given threshold.Similarly, when the ink tank 310 for magenta ink is targeted, theprocessing unit 120 compares the output data in the ink detection areawith 0.55 as a reference value of magenta ink, and determinesabnormality when the difference is equal to or more than a giventhreshold.

The processing unit 120 may also determine the ink characteristics basedon the change characteristics of the light amount in the ink boundaryarea which is the boundary area between the area determined to have theink IK in the ink tank and the area determined to have no ink. In otherwords, the processing unit 120 uses the change in the output data in theink boundary area as the ink characteristics determination featureamount.

For example, the processing unit 120 obtains the maximum value of theinclination of the output data, and detects, as a boundary area, an areawhere the maximum value of the inclination is larger than theinclination threshold. The processing unit 120 obtains the maximum valueof inclination in the boundary area as an ink characteristicsdetermination feature amount. In the example illustrated in FIG. 44, themaximum value of inclination of yellow ink is relatively small, and themaximum value of inclination of magenta ink is large. Thus, theprocessing unit 120 can identify yellow ink and magenta ink bydetermining the maximum value of the inclination. Here, an example inwhich the maximum value of the inclination is used has been exemplified,but other statistical values such as an average value or a median valuemay be used. When using the inclination, the processing unit 120 mayperform processing of specifying the color of ink IK, or may determinenormality/abnormality.

In FIG. 44, the example in which the third correction parameter is usedas the black reference parameter has been described. Thus, the referencevalue used for the ink characteristics determination processing isdifferent according to ink IK, such as the reference value of the yellowink is about 0.55 and the reference value of the magenta ink is about0.40. However, the parameter of the black reference may be a secondcorrection parameter.

For example, in the case of the photoelectric conversion device 322corrected by the second correction parameter acquired in the state wherethe yellow ink is filled, the reference value of the yellow ink becomesa value close to zero. In the case of the photoelectric conversiondevice 322 corrected by the second correction parameter acquired in thestate where magenta ink is filled, the reference value of the magentaink becomes a value close to zero. In this case, the relationship inwhich the output data in the ink detection area when the appropriate inkIK is filled is close to 0, and the output data in the ink detectionarea when the different ink IK is filled deviates from 0 is established.

For example, when magenta ink is erroneously filled in the ink tank 310corresponding to the photoelectric conversion device 322 corrected byusing yellow ink, the output data in the ink detection area becomes anegative value which is small enough to be identified as compared with0. When yellow ink is erroneously filled in the ink tank 310corresponding to the photoelectric conversion device 322 corrected byusing magenta ink, the output data in the ink detection area becomes avalue which is large enough to be identified as compared with 0. Thus,even when correction processing using the second correction parameter isperformed, ink characteristics determination processing can beappropriately executed. Since the reference value becomes a value closeto zero, the numerical range of the output data may be expanded asnecessary so that a negative value can be taken. Similarly, afterperforming the correction processing using the second correctionparameter, the ink characteristics determination processing can beperformed using the inclination in the ink boundary area.

The ink characteristics determined in the ink characteristicsdetermination processing are not limited to color characteristics. Forexample, as described above with reference to FIG. 2, pigment ink anddye ink exist as the same black ink. The pigment ink has high colorreproducibility and quick drying property. The dye ink has a vivid colorand is easy to obtain a glossy feeling. Therefore, it is desirable toproperly use inks of the same color according to the characteristics. Inthe printer, ink characteristics suitable for the printer are differentaccording to various factors such as a physical structure of the printhead 107, an ink ejecting method, a printing speed, and a printingmedium expected to be used. For this reason, there may be a case wheresuitable inks IK are different depending on the model even for pigmentinks of the same color. Therefore, the processing unit 120 determinesthe color material characteristics of the ink as the inkcharacteristics. The color material represents a raw material of colorand specifically represents a pigment or a dye. However, as organicpigments and inorganic pigments are known as pigments, the colormaterials here may represent more specific types and differences inproperties.

FIG. 45 is a diagram comparing output data of the photoelectricconversion devices 322 for two inks IK having different color materialcharacteristics. L1 in FIG. 45 is an example of output data of thephotoelectric conversion device 322 in the case of measuring the inktank 310 filled with magenta dye ink. L2 is an example of output data ofthe photoelectric conversion device 322 in the case of measuring the inktank 310 filled with magenta pigment ink. The horizontal axes of L1 andL2 represent positions in the photoelectric conversion device 322, andthe vertical axes represent output data corresponding to the positions.Similarly to FIG. 44, FIG. 45 illustrates the result of performing thecorrection processing indicated by the above equation (1) using thefirst correction parameter as the white reference parameter and thethird correction parameter as the black reference parameter.

As illustrated in FIG. 45, output data of the photoelectric conversiondevice 322 based on light emission of the red LED 323R is greatlydifferent between magenta dye ink and magenta pigment ink. Therefore,the processing unit 120 determines the ink characteristics based on thelight amount in the ink detection area or the change characteristics ofthe light amount in the ink boundary area. Specifically, the processingunit 120 determines that the ink is the dye ink when the R data in theink detection area is small, and determines that the ink is the pigmentink when the data is large. Alternatively, the processing unit 120determines that the ink is the dye ink when the inclination of the Rdata in the ink boundary area is large, and determines that the ink isthe pigment ink when the data is small.

Alternatively, when the photoelectric conversion device 322 detectslight of the first wavelength and light of the second wavelength, theprocessing unit 120 may determine the ink characteristics based on thefirst characteristics of the light amount of light of the firstwavelength and the second characteristics of the light amount of lightof the second wavelength. In other words, the processing unit 120 usesinformation representing the relationship between the firstcharacteristics and the second characteristics as the inkcharacteristics determination feature amount. As described above, theconfiguration in which the photoelectric conversion device 322 detectslight having a plurality of different wavelengths may be realized by aplurality of light sources 323 having different wavelength bands ofirradiation light, or realized by a combination of a light source havinga wide wavelength band and a filter.

In the example illustrated in FIG. 45, for the magenta dye ink, RGB datahas the same characteristics in both the ink boundary area and the inkdetection area. On the other hand, in the magenta pigment ink, the Rdata is larger than the G data and B data in the ink detection area. Inthe magenta pigment ink, the inclination of the R data is smaller thanthe inclination of the G data and B data in the ink boundary area.Therefore, the processing unit 120 determines that the ink is themagenta dye ink when a first characteristics related to red light and asecond characteristics related to blue light or green light are similar,and determines that the ink is the magenta pigment ink when the firstcharacteristics and second characteristics are not similar.

Specifically, the processing unit 120 obtains a ratio of the R datavalue to the B data value or the G data value in the ink detection area,as the ink characteristics determination feature amount. The processingunit 120 determines that the ink is the magenta dye ink when thedetermined ratio is close to 1, and determines that the ink is themagenta pigment ink when the difference from 1 is large. Alternatively,the processing unit 120 determines the ratio of the inclination of the Rdata to the inclination of the B data or the inclination of the G datain the ink boundary area. The processing unit 120 determines that theink is the magenta dye ink when the determined ratio is close to 1, anddetermines that the ink is the magenta pigment ink when the differencefrom 1 is large.

The determination of the color characteristics and the determination ofthe color material characteristics have been described aboverespectively. However, the processing unit 120 of the present embodimentmay perform the ink characteristics determination processing ofdetermining both the color characteristics and the color materialcharacteristics.

In the above, the example in which the determination based on the firstcharacteristics relating to light of the first wavelength and the secondcharacteristics relating to light of the second wavelength is used forthe determination of the color material characteristics has beendescribed. However, depending on the ink characteristics, determinationbased on the first characteristics and the second characteristics may beused for determination of color characteristics. In other words, theprocessing unit 120 can optionally select which one of the three inkcharacteristics determination feature amounts is used for each of thedetermination of the color characteristics and the determination of thecolor material characteristics.

In addition, the ink characteristics determination processing and theink amount detection processing are not limited to those executedexclusively. The processing unit 120 detects the amount of ink in theink tank based on the change in the light amount in the verticaldirection detected by the photoelectric conversion device 322. That is,both of ink amount detection processing and ink characteristicsdetermination processing may be performed based on the output from thephotoelectric conversion device 322.

In the above, reference data representing the characteristics of the inkIK is known, and the method for determining the ink characteristicsbased on the comparison processing between the ink characteristicsdetermination feature amount obtained from the output data of thephotoelectric conversion device 322 and the given reference value in theprocessing unit 120 has been described. As illustrated with reference toFIGS. 44 and 45, the reference value here is a value of output data inthe ink detection area, the inclination of the output data in the inkboundary area, the relationship between the plurality of characteristicscorresponding to light of the plurality of wavelengths, or the like,which is obtained in advance for the ink IK to be determined.

However, the ink characteristics determination processing of the presentembodiment is not limited to this. Specifically, the photoelectricconversion device 322 performs light detection at a first timing andlight detection at a second timing different from the first timing. Theprocessing unit 120 determines the ink characteristics based on thecharacteristics of the light amount detected at the first timing and thecharacteristics of the light amount detected at the second timing.

As described above, characteristics of the output data of thephotoelectric conversion device 322 are different depending on the colorcharacteristics and the color material characteristics of the ink IK.For this reason, it is estimated that the ink IK has changed between thetwo timings when the output data detected at the second timing changessignificantly with respect to the output data detected at the firsttiming. The change of the output data here represents the change of theink characteristics determination feature amount, and the change in theposition of the interface is not included in the change of the outputdata.

Specifically, when the ink characteristics determination processing atthe second timing is performed after the user filled the wrong ink IK inthe ink tank 310 that has been filled with the appropriate ink IK at thefirst timing, the ink characteristics determination feature amountobtained from the output data changes greatly. Normally, the same inktank 310 is continuously filled with ink IK having the samecharacteristics. That is, in the processing for a given ink tank 310, itis not assumed that the ink characteristics determination feature amountwill change significantly. Therefore, when such a change is detected,the processing unit 120 determines that it is abnormal. For example, theprocessing unit 120 performs processing of notifying the user that thewrong ink IK is filled by using a display unit 150 or the like.

The execution trigger for the ink characteristics determinationprocessing of the present embodiment is optional. For example, theexecution of printing processing may be used as the trigger similarly tothe ink amount detection processing. However, as can be seen from theabove-described example, it is considered that the situation where theinappropriate ink IK is filled occurs when the user performs thereplenishment operation incorrectly. Therefore, the processing unit 120may execute the ink characteristics determination processing using thedetermination that the user has replenished the ink IK as a trigger. Forexample, when it is determined that the ink amount is increased by apredetermined amount or more in the ink amount detection processing, theink characteristics determination processing is started.

5. Electronic Apparatus as Multifunction Peripheral

The electronic apparatus 10 according to the present embodiment may be amultifunction peripheral having a printing function and a scanningfunction. FIG. 46 is a perspective diagram illustrating a state in whichthe case 201 of the scanner unit 200 is pivoted with respect to theprinter unit 100 in the electronic apparatus 10 of FIG. 1. In the stateillustrated in FIG. 46, a document table 202 is exposed. The user sets adocument to be read on the document table 202, and then instructs theexecution of scanning by using the operation unit 160. The scanner unit200 reads an image of the document by performing the reading processingwhile moving the image reading unit (not illustrated) based on aninstruction operation by the user. The scanner unit 200 is not limitedto a flat bed type scanner. For example, the scanner unit 200 may be ascanner having an auto document feeder (ADF) (not illustrated). Theelectronic apparatus 10 may be an apparatus having both the flat bedtype scanner and a scanner having the ADF.

The electronic apparatus 10 includes the image reading unit including afirst sensor module, the ink tank 310, the print head 107, the secondsensor module, and the processing unit 120. The image reading unit readsthe document by using a first sensor module including m, m being aninteger of two or more, linear image sensor chips. The second sensormodule includes n, n being an integer of 1 or more and n<m, linear imagesensor chips, and detects light incident from the ink tank 310. Theprocessing unit 120 detects the amount of ink in the ink tank based onthe output of the second sensor module. The first sensor module is asensor module used for scanning an image in the scanner unit 200, andthe second sensor module is a sensor module used for the ink amountdetection processing in the ink tank unit 300.

Both the first sensor module and the second sensor module include alinear image sensor chip. The specific configuration of the linear imagesensor chip is the same as that of the photoelectric conversion device322 described above, and a plurality of photoelectric conversionelements are arranged side by side in a predetermined direction. Sincethe linear image sensor used for the image reading and the linear imagesensor used for the ink amount detection processing can be used incommon, it is possible to improve the manufacturing efficiency of theelectronic apparatus 10.

However, the first sensor module needs to have a length corresponding tothe document size to be read. Since the length of one linear imagesensor chip is about 10 mm, for example, the first sensor module needsto include at least two linear image sensor chips. On the other hand,the second sensor module has a length corresponding to the target rangeof ink amount detection. The target range of ink amount detection can bevariously modified but is generally shorter than that of the imagereading. That is, as described above, m is an integer of 2 or more, n isan integer of 1 or more, and m>n. Thus, the number of linear imagesensor chips can be appropriately set according to the application.

The difference between the first sensor module and the second sensormodule is not limited to the number of linear image sensor chips. The mlinear image sensor chips of the first sensor module are provided suchthat the longitudinal direction thereof corresponds to the horizontaldirection. The n linear image sensor chips of the second sensor moduleare provided such that the longitudinal direction thereof corresponds tothe vertical direction. Since the second sensor module needs to detectthe interface of the ink IK as described above, the longitudinaldirection corresponds to the vertical direction.

On the other hand, in consideration of reading the image of thedocument, the longitudinal direction of the first sensor module needs tobe the horizontal direction. This is because when the longitudinaldirection of the first sensor module is set to the vertical direction,it is difficult to stably set the document on the document table 202, orit is difficult to stabilize the document posture when the document istransported by the ADF. By setting the longitudinal direction of thelinear image sensor chip in accordance with the application, the inkamount detection processing and the image reading can be performedappropriately.

The image reading unit may include a third sensor module having k, kbeing an integer of k>n, linear image sensor chips. The electronicapparatus 10 includes, as operation modes, a first mode for reading adocument on the document table using the first sensor module and asecond mode for reading the document while transporting the documentusing the third sensor module. In this way, it is possible to realizethe electronic apparatus 10 having both the flat bed type scanner andthe scanner having the feeder. At this time, it is possible to make themanufacturing of the electronic apparatus 10 more efficient byconfiguring both sensor modules of the two scanners with linear imagesensor chips. Since the third sensor module is also used for imagereading similarly to the first sensor module, the number of linear imagesensor chips is larger than that of the second sensor module.

Alternatively, the image reading unit may use the first sensor modulefor reading by the ADF. Further, a fourth sensor module having acharge-coupled device (CCD) image sensor chip may be included. Thelinear image sensor chip included in the first sensor module and thelinear image sensor chip included in the second sensor module aremetal-oxide-semiconductor (MOS) image sensor chips. In this case, theelectronic apparatus 10 includes, as operation modes, the first mode forreading the document on the document table by using the fourth sensormodule and the second mode for reading the document while transportingthe document by using the first sensor module.

Even in this case, it is possible to realize the electronic apparatus 10having both the flat bed type scanner and the scanner having the feeder.At this time, the fourth sensor module for the first mode is a CCDsystem, so that an image with deep depth of field can be read. That is,as the fourth sensor module, the sensor module suitable for a method forreading the document on the document table can be used.

The first sensor module and the second sensor module have differentconfigurations of optical separators. For example, the first sensormodule has a first optical separator which is a lens module. On theother hand, in the ink tank 310, a second optical separator forseparating light incident on the second sensor module in the verticaldirection is provided on the side surface. That is, the opticalseparator for the second sensor module may be a separator of a simpleconfiguration provided on the wall surface of the ink tank 310 asdescribed above with reference to FIGS. 18 to 21. In this way, it ispossible to provide an appropriate optical separator according to theaccuracy required for each sensor module.

Alternatively, the first sensor module may have the first opticalseparator as a lens module, and the second sensor module may have thesecond optical separator as a slit. The slit here is, for example, aresin slit 330 illustrated in FIG. 17. Even in this case, it is possibleto provide an appropriate optical separator according to the accuracyrequired for each sensor module.

The first sensor module operates at a first operating frequency, and thesecond sensor module operates at a second operating frequency lower thanthe first operating frequency. In image reading, it is necessary tocontinuously acquire signals corresponding to many pixels and to formimage data by performing A/D conversion processing, correctionprocessing, or the like of the signals. Therefore, it is desirable toperform reading by the first sensor module at high speed. On the otherhand, the ink amount detection is less likely to be a problem even whenthe number of photoelectric conversion elements is small and it takes acertain amount of time to detect the ink amount. By setting theoperating frequency for each sensor module, each sensor module can beoperated at an appropriate speed.

The position of the light source may be changed between the first sensormodule and the second sensor module. For example, the first sensormodule has a light source provided in a direction along the longitudinaldirection of the m linear image sensor chips, and the second sensormodule has a light source provided in a direction intersecting thelongitudinal direction of the n linear image sensor chips. As describedabove, the length of the second sensor module in the longitudinaldirection is shorter than that of the first sensor module, and thereading accuracy is not required as compared with the first sensormodule. Therefore, as illustrated in FIGS. 23 and 24, the light source323 and the photoelectric conversion device 322 can be arranged side byside in the direction along the X-axis. That is, an appropriate lightsource arrangement can be used according to the accuracy required foreach sensor module.

The first sensor module includes a light guide and a light sourceprovided at the end of the light guide. As illustrated in FIGS. 10 to12, light from the light source corresponding to the first sensor moduleenters the light guide at an angle at which total reflection is likelyto occur. Since the entire light guide can be uniformly illuminated,reading accuracy by the first sensor module can be enhanced. The secondsensor module may include a light guide 324 as illustrated in FIGS. 23and 24, or the light guide 324 may be omitted.

As described above, the printer according to the present embodimentincludes an ink tank, a print head, a substrate, a light source, aphotoelectric conversion device, and a processing unit. The print headperforms printing by using ink in the ink tank. The light source isprovided at the substrate and irradiates the ink tank with light fromthe side of the ink tank. The photoelectric conversion device isprovided at the substrate and detects light incident from the ink tankin a period during which the light source emits light. The processingunit detects the amount of ink in the ink tank based on the output ofthe photoelectric conversion device.

In the printer according to the present embodiment, processing ofdetecting the amount of ink in the ink tank is performed based on thelight source and the photoelectric conversion device mounted on the samesubstrate. Thus, the manufacture of the unit including the light sourceand the photoelectric conversion device and the arrangement in theelectronic apparatus are facilitated, and the ink amount can be detectedappropriately by using the efficient configuration.

Further, the photoelectric conversion device may be a linear imagesensor.

In this way, the ink amount can be accurately detected by detecting theink amount by using a plurality of photoelectric conversion elementsarranged in a predetermined direction.

Further, a longitudinal direction of the linear image sensor maycorrespond to the vertical direction.

In this way, the ink amount can be accurately detected by detecting theink amount by using a plurality of photoelectric conversion elementsarranged in the vertical direction.

Further, the printer may also include a second linear image sensorprovided on the longitudinal direction side of the linear image sensor.

In this way, by using a plurality of linear image sensors arranged inthe vertical direction, the range to be the target of ink amountdetection can be expanded.

Further, the printer may also include a light shielding wall providedbetween the light source and the photoelectric conversion device.

In this way, since direct light from the light source is prevented fromentering the photoelectric conversion device, the accuracy of ink amountdetection can be improved.

Further, the light source may be disposed in a first direction which isthe horizontal direction, with respect to the photoelectric conversiondevice. The first direction here is, for example, a direction along theX-axis.

In this way, the positional relationship between the light source andthe photoelectric conversion device can be set flexibly.

Further, at least a portion, facing the photoelectric conversion device,of the inner wall of the ink tank may have higher ink repellency thanthe outer wall of the ink tank.

In this way, the decrease in accuracy of ink amount detection caused byink droplets adhering to the inner wall of the ink tank can besuppressed.

Further, the printer may also include a second substrate provided with aprocessing unit and an analog front end (AFE). The AFE performs A/Dconversion of the analog signal from the photoelectric conversiondevice.

In this way, it is possible to provide a substrate for the processingunit and the AFE separately from the substrate on which the light sourceand the photoelectric conversion device are mounted.

Further, the printer may include a second substrate at which theprocessing unit is provided, and the processing unit may output acontrol signal for controlling the photoelectric conversion device.

In this way, the photoelectric conversion device can be controlled byusing the processing unit, and the substrate for the processing unit canbe provided separately from the substrate on which the light source andthe photoelectric conversion device are mounted.

Further, the ink tank includes a filling port into which ink is filledby the user, and a discharging port for discharging ink toward the printhead. The substrate is closer to the discharging port than to thefilling port.

In this way, the photoelectric conversion device can be provided at aposition relatively close to the discharging port. Therefore, it ispossible to detect the ink amount for an appropriate region in the inktank.

Further, the printer includes a window portion for visually recognizingink in the ink tank. The window portion is closer to the filling portthan to the discharging port.

In this way, the direction in which the photoelectric conversion deviceis provided and the direction in which the window portion is providedcan be separated with respect to the ink tank. Thus, when the uservisually recognizes the ink amount through the window portion, theobstruction of the visual recognition by the photoelectric conversiondevice can be suppressed.

Although the present embodiment has been described in detail asdescribed above, a person skilled in the art can easily understand thatmany modifications that do not substantially depart from the novelmatters and effects of the present embodiment are possible. Accordingly,all such modifications are intended to be included within the scope ofthe present disclosure. For example, a term described at least oncetogether with a different term having a broader meaning or the samemeaning in the specification or the drawings can be replaced with thedifferent term anywhere in the specification or the drawings. Allcombinations of the present embodiment and the modifications are alsoincluded in the scope of the present disclosure. The configurations andoperations of the electronic apparatus, printer unit, scanner unit, inktank unit, and the like are not limited to those described in thepresent embodiment, and various modifications can be made.

For example, in the photoelectric conversion device, the linear imagesensors may be arranged in the horizontal direction or obliquely fromthe horizontal direction. In this case, by arranging a plurality oflinear image sensors in the vertical direction or moving them in thevertical direction relative to the ink tank, the same information aswhen the linear image sensors are arranged in the vertical direction canbe obtained. The photoelectric conversion device may be one or more areaimage sensors. In this way, one image sensor may be straddled across aplurality of ink tanks. In addition, the photoelectric conversion devicemay obtain information from all ink tanks by using one linear imagesensor by disposing one linear image sensor in the vertical directionand relatively moving the substrate having the photoelectric conversiondevice and the light source and the ink tank in the direction in whichthe ink tanks are arranged. Of course, the light source in this case maybe provided separately from the substrate provided with thephotoelectric conversion device, and the light source may not berelatively moved.

What is claimed is:
 1. A printer comprising: an ink tank; a print head performing printing by using ink in the ink tank; a substrate; a light source provided on the substrate and irradiating the ink tank with light from a side of the ink tank; a photoelectric conversion device provided on the substrate and detecting light incident from the ink tank in a period during which the light source emits light; a light shielding wall provided on the substrate between the light source and the photoelectric conversion device; and a processing unit detecting an amount of ink in the ink tank based on an output of the photoelectric conversion device.
 2. The printer according to claim 1, wherein the photoelectric conversion device is a linear image sensor.
 3. The printer according to claim 2, wherein the linear image sensor is provided such that a longitudinal direction of the image sensor corresponds to a vertical direction.
 4. The printer according to claim 2, further comprising: a second linear image sensor provided on a longitudinal direction side of the linear image sensor.
 5. The printer according to claim 1, wherein the light source is disposed in a first direction which is a horizontal direction with respect to the photoelectric conversion device.
 6. The printer according to claim 1, wherein at least a portion, facing the photoelectric conversion device, of an inner wall of the ink tank has higher ink repellency than an outer wall of the ink tank.
 7. The printer according to claim 1, further comprising: a second substrate provided with the processing unit and an analog front end (AFE), wherein the AFE performs analog-to-digital conversion of an analog signal from the photoelectric conversion device.
 8. The printer according to claim 1, further comprising: a second substrate provided with the processing unit, wherein the processing unit outputs a control signal for controlling the photoelectric conversion device.
 9. The printer according to claim 1, wherein the ink tank includes a filling port into which the ink is filled by a user and a discharging port for discharging the ink toward the print head, and the substrate is closer to the discharging port than to the filling port.
 10. The printer according to claim 9, further comprising: a window portion for visually recognizing ink in the ink tank, wherein the window portion is closer to the filling port than to the discharging port.
 11. The printer according to claim 1, wherein a plurality of the ink tanks are arranged in a first direction, and the processing unit detects an amount of ink in each of the plurality of ink tanks based on an output of the photoelectric conversion device by relatively moving the substrate and the ink tanks in the first direction. 